A temperature controlled oscillator is provided with a circuit substrate having a crystal resonator, an oscillating circuit, and a temperature control circuit, arranged on one or both principal surfaces, and a container main body that accommodates the circuit substrate and has mount terminals on an outer bottom surface thereof. The temperature control circuit includes at least a first temperature sensor that detects an operating temperature of the crystal resonator, a second temperature sensor that detects a surrounding temperature of the container main body, and a heating resistor that applies heat to the crystal resonator, and lead wires extend from the circuit substrate and are connected electrically to the mount terminals. An insulation groove that passes through the circuit substrate in a thickness direction is formed between: a first lead wire closest to the second temperature sensor, and the second temperature sensor; and the heating resistor.