PURPOSE: To provide an anomaly detecting device for a step tread which can detect the damage of the projection part of the step tread of an escalator and detecting the damage, even when an elevator is in operation.

CONSTITUTION: A (b) contact point which is opened by the drop of an anomaly detecting roller 13 into a cut part 5 and an anomaly detecting relay connected with the (b) contact point are installed. and an anomaly lamp is connected with an another (b) contact point which is closed by the cut-off of the excitation of the anomaly detecting relay, and the anomaly is informed.