Abstract: In a frequency-to-voltage converting circuit, a clamping frequency is maintained constant without being adversely influenced by circuit constants, and temperature characteristics. The frequency-to-voltage converting apparatus has voltage converting means for converting a frequency of an input pulse signal into a voltage, arranged by frequency judging means for judging whether or not the frequency of the input pulse signal reaches a predetermined clamping frequency. Setting pulse signal generating means outputs a setting pulse signal having the clamping frequency, and means for causing the voltage converting means to convert the frequency of the input pulse signal into the voltage when the frequency of the input pulse signal does not reach the clamping frequency based on a judgement result of the frequency judging means.