To provide an abnormality determination device for a pressure sensor capable of securing more opportunities for abnormality determination of the pressure sensor than a conventional device.

A fuel supply mechanism includes an electric fuel pump, a pressure regulator capable of adjusting pressure of fuel pumped to an engine to a set pressure that is preset, and a pressure sensor for detecting a fuel pressure, wherein an abnormality determination device for a pressure sensor which determines abnormality in the pressure sensor has an ECU for calculating an actual pressure change (inclination) ΔPf based on a detection value detected by the pressure sensor when varying a relief flow amount of fuel recirculated to a fuel tank via a relief passage while a fuel consumption is maintained constant in the engine, and determines abnormality in the pressure sensor based on a calculated actual pressure change (inclination) ΔPf and a predetermined reference fuel pressure change (inclination) ΔPb.