To provide a capacitance type humidity converter having precision and stability of a level required as a device for public welfare and good cost performance.

In this capacitance type humidity converter, a square wave output of a square wave oscillating circuit connected so that a capacitance type humidity sensor determines an oscillating frequency is guided to an integrating circuit, and a triangular wave output of the integrating circuit is connected to a peak holding circuit. In the converter, when the measured humidity of the capacitance type humidify sensor is maximum, a time constant of the integrating circuit is selected so that the square wave output of the square wave oscillating circuit and the triangular wave output of the integrating circuit are substantially in the same phase.