A stroke sensor abnormality determining apparatus includes a stroke sensor for detecting a stroke of a brake pedal by detecting an electric signal that varies in response to the stroke of the brake pedal, a deceleration calculating unit for calculating a total target value, which is correlated with a target deceleration of a vehicle, based on at least the stroke, and an abnormality determining unit for determining whether or not an abnormality of the stroke sensor occurs, based on the electric signal detected by the stroke sensor, the abnormality determining unit being configured so that a signal indicating the abnormality of the stroke sensor can be outputted when the abnormality is determined to have occurred in the stroke sensor.