diff --git a/src/main/resources/mappers/estimate/estimateMapper.xml b/src/main/resources/mappers/estimate/estimateMapper.xml
index f59e13f8..2e7aaa48 100644
--- a/src/main/resources/mappers/estimate/estimateMapper.xml
+++ b/src/main/resources/mappers/estimate/estimateMapper.xml
@@ -466,7 +466,8 @@
                  GROUP BY CIRCUIT_NO, CIRCUIT_ITEM_ID, CIRCUIT_CFG, CIRCUIT_SUM, PNOW_W
                      )
 
-                SELECT ROUND((SUM(MIN_VALUE) / 1000), 4)  AS CERT_VOL_KW
+                -- 2026-05-22: FLOAT ROUND 결과의 IEEE754 잔여(예: 5.5600000000000005) 차단 위해 DECIMAL(18,4) 캐스팅
+                SELECT CAST(ROUND((SUM(MIN_VALUE) / 1000), 4) AS DECIMAL(18,4))  AS CERT_VOL_KW
                 FROM CIRCUIT_AGG
 
         ]]>