Disclosed is a physical quantity detection device that is provided with: an oscillator that outputs detection signals corresponding to a physical quantity; and a drive circuit that drives the oscillator to oscillate. The drive circuit includes: an oscillation detection unit that detects the oscillating state or non-oscillating state of the oscillator on the basis of drive signals of the oscillator; a start-up oscillation unit that assists oscillation operations of the oscillator in the cases where the detection results obtained from the oscillation detection unit indicate the non-oscillating state; and a number of switching times monitoring unit that detects that the number of times the oscillating state and the non-oscillating state have switched has become larger than a set upper limit number of times, said oscillating state and non-oscillating state having been detected by the oscillation detection unit.