A temperature control circuit of oven-controlled crystal oscillator includes a heater resistor, a first resistor, a thermistor, a second resistor, a third resistor, a differential amplifier, a PNP-type power transistor, and a PNP-type current-limiting transistor. The thermistor outputs a voltage depending on a temperature. The differential amplifier amplifies a difference between the voltage received by the one input terminal and the voltage received by the other and output as a control voltage. The PNP-type power transistor includes an emitter where the other end of the heater resistor is connected, a base that receives an output of the differential amplifier, and a grounded collector. The PNP-type current-limiting transistor has an emitter where a power voltage is supplied, a base that receives a voltage between the other end of the heater resistor and the emitter of the power transistor, and a collector connected to the base of the power transistor.