PURPOSE: To provide a mold protecting method for an injection molding machine wherein damage of a mold can be prevented regardless of size of a molded piece and structure of the mold.

CONSTITUTION: In a mold protecting method for an injection molding machine 1 having molds 8 attached to a movable platen 6 and a fixed platen 7, mold closing action for fitting the molds 8 by the movable platen 6, mold clamping action for blocking the fitted molds 8 so as not to open, and mold opening action for dividing the molds 8 are provided. In this method, a mold protecting block from the start of the mold closing action to the start of the mold clamping action is divided into a plurality of blocks. In each of the divided blocks, abnormality detecting means for detecting abnormality based on a difference between a preset allowable time and an actually elapsed elapsed-time are provided. Based on the signal from the abnormality detecting means, the mold closing action is stopped.