To provide a method for repairing the defect on an aluminum cast member by which the deformation, residual stress and thermally affected part after repairing are hardly created, the entrapment of inclusions into the jointed part scarcely occurs and any heat treatment after repairing is unnecessary.

This repairing method is performed by repairing the casting defect on the cast member manufactured of the aluminum alloy by a plastic flow method in which, while rotating a tool being harder than this member, the tool is inserted into the defective part. In this process, the tool is inserted to the whole depth of the defective part while gradually inserting the tool from the sound part in this member and the depth of the tool is gradually made shallower after reaching the final position of the defective part.