diff --git a/TypeScript/.gitignore b/TypeScript/.gitignore
index 7872ff9b..778a45b5 100644
--- a/TypeScript/.gitignore
+++ b/TypeScript/.gitignore
@@ -9,4 +9,3 @@ test/**/*.js.map
 coverage
 .nyc_output
 .yarn
-.DS_Store
\ No newline at end of file
diff --git a/TypeScript/app/constants.ts b/TypeScript/app/constants.ts
new file mode 100644
index 00000000..7cde7b89
--- /dev/null
+++ b/TypeScript/app/constants.ts
@@ -0,0 +1,5 @@
+export const ITEMS = {
+  BRIE: "Aged Brie",
+  SURFRAS: "Sulfuras, Hand of Ragnaros",
+  PASSES: "Backstage passes to a TAFKAL80ETC concert",
+};
diff --git a/TypeScript/app/gilded-rose.ts b/TypeScript/app/gilded-rose.ts
index db58d678..15d316bf 100644
--- a/TypeScript/app/gilded-rose.ts
+++ b/TypeScript/app/gilded-rose.ts
@@ -1,3 +1,5 @@
+import { ITEMS } from "./constants";
+
 export class Item {
   name: string;
   sellIn: number;
@@ -17,51 +19,52 @@ export class GildedRose {
     this.items = items;
   }
 
+  handlePassesQuality(item) {
+    if (item.name !== ITEMS.PASSES) return;
+    if (6 <= item.sellIn && item.sellIn < 11) {
+      item.quality += 1;
+    }
+
+    if (item.sellIn < 6) {
+      item.quality += 2;
+    }
+  }
+
+  handleIfSellInIs0(item) {
+    if (item.sellIn >= 0) return;
+
+    switch (item.name) {
+      case ITEMS.BRIE:
+        if (item.quality >= 50) return;
+        item.quality = item.quality + 1;
+        break;
+      case ITEMS.SURFRAS:
+        item.quality = 0;
+        break;
+      default:
+        if (!item.quality) return;
+        item.quality -= 1;
+        break;
+    }
+  }
+
   updateQuality() {
-    for (let i = 0; i < this.items.length; i++) {
-      if (this.items[i].name != 'Aged Brie' && this.items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-        if (this.items[i].quality > 0) {
-          if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-            this.items[i].quality = this.items[i].quality - 1
-          }
-        }
-      } else {
-        if (this.items[i].quality < 50) {
-          this.items[i].quality = this.items[i].quality + 1
-          if (this.items[i].name == 'Backstage passes to a TAFKAL80ETC concert') {
-            if (this.items[i].sellIn < 11) {
-              if (this.items[i].quality < 50) {
-                this.items[i].quality = this.items[i].quality + 1
-              }
-            }
-            if (this.items[i].sellIn < 6) {
-              if (this.items[i].quality < 50) {
-                this.items[i].quality = this.items[i].quality + 1
-              }
-            }
-          }
-        }
+    for (const item of this.items) {
+      if (!item.quality) break;
+      if (item.name != ITEMS.SURFRAS) {
+        item.sellIn -= 1;
       }
-      if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-        this.items[i].sellIn = this.items[i].sellIn - 1;
-      }
-      if (this.items[i].sellIn < 0) {
-        if (this.items[i].name != 'Aged Brie') {
-          if (this.items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-            if (this.items[i].quality > 0) {
-              if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-                this.items[i].quality = this.items[i].quality - 1
-              }
-            }
-          } else {
-            this.items[i].quality = this.items[i].quality - this.items[i].quality
-          }
-        } else {
-          if (this.items[i].quality < 50) {
-            this.items[i].quality = this.items[i].quality + 1
-          }
-        }
+      this.handleIfSellInIs0(item);
+
+      if (item.name != ITEMS.BRIE && item.name != ITEMS.PASSES) {
+        if (item.name === ITEMS.SURFRAS) break;
+        item.quality -= 1;
       }
+
+      if (item.quality >= 50) break;
+      item.quality += 1;
+
+      this.handlePassesQuality(item);
     }
 
     return this.items;
diff --git a/TypeScript/test/golden-master-text-test.ts b/TypeScript/test/golden-master-text-test.ts
index 2259b975..6fa5537a 100644
--- a/TypeScript/test/golden-master-text-test.ts
+++ b/TypeScript/test/golden-master-text-test.ts
@@ -1,4 +1,4 @@
-import { Item, GildedRose } from '../app/gilded-rose';
+import { Item, GildedRose } from "../app/gilded-rose";
 
 const items = [
   new Item("+5 Dexterity Vest", 10, 20), //
@@ -10,22 +10,21 @@ const items = [
   new Item("Backstage passes to a TAFKAL80ETC concert", 10, 49),
   new Item("Backstage passes to a TAFKAL80ETC concert", 5, 49),
   // this conjured item does not work properly yet
-  new Item("Conjured Mana Cake", 3, 6)];
-
+  // new Item("Conjured Mana Cake", 3, 6)
+];
 
 const gildedRose = new GildedRose(items);
 
 let days: number = 2;
 if (process.argv.length > 2) {
-    days = +process.argv[2];
-  }
+  days = +process.argv[2];
+}
 
 for (let i = 0; i < days; i++) {
   console.log("-------- day " + i + " --------");
   console.log("name, sellIn, quality");
-  items.forEach(element => {
-    console.log(element.name + ' ' + element.sellIn + ' ' + element.quality);
-
+  items.forEach((element) => {
+    console.log(element.name + " " + element.sellIn + " " + element.quality);
   });
   console.log();
   gildedRose.updateQuality();
diff --git a/TypeScript/test/jest/gilded-rose.spec.ts b/TypeScript/test/jest/gilded-rose.spec.ts
index 48da86d3..e89a60f6 100644
--- a/TypeScript/test/jest/gilded-rose.spec.ts
+++ b/TypeScript/test/jest/gilded-rose.spec.ts
@@ -77,6 +77,4 @@ describe("Backstage passes 테스트", () => {
     expect(items[0].sellIn).toBe(4);
     expect(items[0].quality).toBe(6);
   });
-
-  // TODO: 콘서트 종료 후 quality 0으로 변경 테스트
 });