Piezoelectric actuator drive circuit and fuel injection system

A piezoelectric actuator drive circuit (2) has an abnormality detection circuit section (29E, 29F). The abnormality detection circuit section (29E, 29F) is provided with a voltage detection means (31) for detecting the voltage (Vcom) of a connection terminal (201E, 201F) on the non-ground side and a comparison means (32) for generating a comparison signal (Vcomp) to check whether a detected voltage is higher than a reference voltage (Vref) or not based on the comparison result between the detected voltage and the reference voltage. If the detected voltage is lower than the reference voltage, it is determined that a cable (203A-203F) is disconnected.