diff --git a/src/main/java/gc/mda/signal_batch/global/websocket/service/ChunkedTrackStreamingService.java b/src/main/java/gc/mda/signal_batch/global/websocket/service/ChunkedTrackStreamingService.java
index 0edb022..8fc3e14 100644
--- a/src/main/java/gc/mda/signal_batch/global/websocket/service/ChunkedTrackStreamingService.java
+++ b/src/main/java/gc/mda/signal_batch/global/websocket/service/ChunkedTrackStreamingService.java
@@ -36,6 +36,7 @@ import java.util.function.Consumer;
 import gc.mda.signal_batch.global.websocket.dto.QueryStatusUpdate;
 import gc.mda.signal_batch.global.websocket.dto.ViewportFilter;
 import org.springframework.scheduling.annotation.Async;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -82,6 +83,9 @@ public class ChunkedTrackStreamingService {
     private final Map<String, BackpressureMetrics> queryMetrics = new ConcurrentHashMap<>();
     @SuppressWarnings("unused")
     private volatile int currentChunkSizeKB = MAX_MESSAGE_SIZE_KB;
+
+    // 쿼리별 취소 플래그 관리
+    private final ConcurrentHashMap<String, AtomicBoolean> queryCancelFlags = new ConcurrentHashMap<>();
     
     // track_geom 고정 사용
 
@@ -855,6 +859,10 @@ public class ChunkedTrackStreamingService {
                 return;
             }
 
+            // 취소 플래그 등록
+            AtomicBoolean cancelFlag = new AtomicBoolean(false);
+            queryCancelFlags.put(queryId, cancelFlag);
+
             log.info("Starting chunked streaming for query: {}", queryId);
             queryStartTime = System.currentTimeMillis();
             processedTimeRanges.clear();
@@ -887,6 +895,13 @@ public class ChunkedTrackStreamingService {
             for (TableStrategy strategy : new TableStrategy[]{TableStrategy.DAILY, TableStrategy.HOURLY, TableStrategy.FIVE_MINUTE}) {
                 if (!strategyMap.containsKey(strategy)) continue;
 
+                // 취소 확인
+                if (cancelFlag.get()) {
+                    log.info("Query {} cancelled before processing strategy {}", queryId, strategy);
+                    statusConsumer.accept(new QueryStatusUpdate(queryId, "CANCELLED", "Query cancelled by user", 0.0));
+                    return;
+                }
+
                 List<TimeRange> ranges = strategyMap.get(strategy);
                 log.info("Processing {} strategy with {} ranges", strategy, ranges.size());
 
@@ -1182,7 +1197,8 @@ public class ChunkedTrackStreamingService {
                     0.0
             ));
         } finally {
-            // 리소스 반환 (순서: 글로벌 슬롯 → 세션 카운트 → 메트릭스)
+            // 리소스 반환 (순서: 취소 플래그 → 글로벌 슬롯 → 세션 카운트 → 메트릭스)
+            queryCancelFlags.remove(queryId);
             if (slotAcquired) {
                 activeQueryManager.releaseQuerySlot(queryId);
             }
@@ -1198,7 +1214,11 @@ public class ChunkedTrackStreamingService {
      */
     public void cancelQuery(String queryId) {
         log.info("Cancelling chunked query: {}", queryId);
-        // TODO: Phase 2.1에서 실제 취소 로직 구현
+        AtomicBoolean flag = queryCancelFlags.get(queryId);
+        if (flag != null) {
+            flag.set(true);
+            log.info("Cancel flag set for chunked query: {}", queryId);
+        }
         cleanupQueryMetrics(queryId);
     }
 
@@ -2686,6 +2706,14 @@ public class ChunkedTrackStreamingService {
             return false;
         }
 
+        // 1. queryCancelFlags 확인 (cancelQuery() 호출 시 설정됨)
+        for (Map.Entry<String, AtomicBoolean> entry : queryCancelFlags.entrySet()) {
+            if (entry.getValue().get()) {
+                return true;
+            }
+        }
+
+        // 2. ActiveQueryManager 확인 (세션 종료 시 설정됨)
         ActiveQueryManager.ActiveQuery query = activeQueryManager.getQuery(sessionId);
         return query != null && query.isCancelled();
     }