An electronic circuit device comprises an output part, which includes at least three phase parts and a first temperature sensor and a second temperature sensor, which output detection signals corresponding to temperatures of the output part. Each phase part includes two high-side and low-side switching elements. The first temperature sensor is located at a position between the first phase part and the second phase part. The second temperature sensor is located at a position between the second phase part and the third phase part. The electronic circuit device further comprises a control circuit part, which specifies a phase part of overheat among the phase parts based on the detection signals of the first temperature sensor and the second temperature sensor.