diff --git a/frontend/src/app/portfolio/[id]/page.tsx b/frontend/src/app/portfolio/[id]/page.tsx
index 8e6063b..465d5e1 100644
--- a/frontend/src/app/portfolio/[id]/page.tsx
+++ b/frontend/src/app/portfolio/[id]/page.tsx
@@ -128,6 +128,7 @@ export default function PortfolioDetailPage() {
     tx_type: 'buy',
     quantity: '',
     price: '',
+    totalAmount: '',
     executed_at: '',
     memo: '',
   });
@@ -251,7 +252,7 @@ export default function PortfolioDetailPage() {
         memo: txForm.memo || null,
       });
       setTxModalOpen(false);
-      setTxForm({ ticker: '', tx_type: 'buy', quantity: '', price: '', executed_at: '', memo: '' });
+      setTxForm({ ticker: '', tx_type: 'buy', quantity: '', price: '', totalAmount: '', executed_at: '', memo: '' });
       setTxManualTicker(false);
       await Promise.all([fetchPortfolio(), fetchTransactions()]);
     } catch (err) {
@@ -826,27 +827,60 @@ export default function PortfolioDetailPage() {
                 </SelectContent>
               </Select>
             </div>
+            <div className="space-y-2">
+              <Label htmlFor="tx-quantity">수량</Label>
+              <Input
+                id="tx-quantity"
+                type="number"
+                min="1"
+                placeholder="0"
+                value={txForm.quantity}
+                onChange={(e) => {
+                  const qty = e.target.value;
+                  const updates: Partial<typeof txForm> = { quantity: qty };
+                  // Recalculate total if price exists
+                  if (txForm.price && qty) {
+                    updates.totalAmount = String(Math.round(parseFloat(txForm.price) * parseInt(qty, 10)));
+                  }
+                  setTxForm({ ...txForm, ...updates });
+                }}
+              />
+            </div>
             <div className="grid grid-cols-2 gap-4">
               <div className="space-y-2">
-                <Label htmlFor="tx-quantity">수량</Label>
-                <Input
-                  id="tx-quantity"
-                  type="number"
-                  min="1"
-                  placeholder="0"
-                  value={txForm.quantity}
-                  onChange={(e) => setTxForm({ ...txForm, quantity: e.target.value })}
-                />
-              </div>
-              <div className="space-y-2">
-                <Label htmlFor="tx-price">가격</Label>
+                <Label htmlFor="tx-price">1주당 가격</Label>
                 <Input
                   id="tx-price"
                   type="number"
                   min="1"
                   placeholder="0"
                   value={txForm.price}
-                  onChange={(e) => setTxForm({ ...txForm, price: e.target.value })}
+                  onChange={(e) => {
+                    const price = e.target.value;
+                    const updates: Partial<typeof txForm> = { price };
+                    if (price && txForm.quantity) {
+                      updates.totalAmount = String(Math.round(parseFloat(price) * parseInt(txForm.quantity, 10)));
+                    }
+                    setTxForm({ ...txForm, ...updates });
+                  }}
+                />
+              </div>
+              <div className="space-y-2">
+                <Label htmlFor="tx-total">총 금액</Label>
+                <Input
+                  id="tx-total"
+                  type="number"
+                  min="1"
+                  placeholder="0"
+                  value={txForm.totalAmount}
+                  onChange={(e) => {
+                    const total = e.target.value;
+                    const updates: Partial<typeof txForm> = { totalAmount: total };
+                    if (total && txForm.quantity && parseInt(txForm.quantity, 10) > 0) {
+                      updates.price = String(Math.round(parseFloat(total) / parseInt(txForm.quantity, 10)));
+                    }
+                    setTxForm({ ...txForm, ...updates });
+                  }}
                 />
               </div>
             </div>