There is provided a pressure detection device including: a pressure detection element which receives pressure so as to output a detection signal corresponding to the pressure P; and a processing circuit which processes and outputs the detection signal output from the pressure detection element, where the processing circuit includes: a voltage transformation circuit which only transforms a power supply voltage fed from an external power supply so as to obtain a first reference voltage with a predetermined voltage value; an integrator circuit which uses the first reference voltage as an operation reference to perform integral processing on the detection signal so as to convert the detection signal into a voltage waveform; and at least one or more amplifier circuits which use a second reference voltage with a predetermined voltage value as an operation reference to perform amplification processing on an output signal from the integrator circuit.