diff --git a/src/otx/algorithms/classification/adapters/mmcls/datasets/otx_datasets.py b/src/otx/algorithms/classification/adapters/mmcls/datasets/otx_datasets.py
index ad950763948..6f0ba443ebf 100644
--- a/src/otx/algorithms/classification/adapters/mmcls/datasets/otx_datasets.py
+++ b/src/otx/algorithms/classification/adapters/mmcls/datasets/otx_datasets.py
@@ -264,7 +264,7 @@ def evaluate(
 
             confusion_matrices = []
             for cls_idx in cls_index:
-                group_labels_idx = set([cls_idx - 1])
+                group_labels_idx = set([cls_idx])
                 y_true = [int(not group_labels_idx.issubset(true_labels)) for true_labels in true_label_idx]
                 y_pred = [int(not group_labels_idx.issubset(pred_labels)) for pred_labels in pred_label_idx]
                 matrix_data = sklearn_confusion_matrix(y_true, y_pred, labels=list(range(len([0, 1]))))