An oscillator includes a container, an oscillation element housed in the container, a heating circuit housed in the container, and adapted to control a temperature of the oscillation element, a temperature detection circuit housed in the container, a temperature control circuit housed in the container, and adapted to control the heating circuit based on an output of the temperature detection circuit, at least one connecting wire housed in the container, and electrically connects a ground of the temperature detection circuit and a ground of the temperature control circuit to each other, and a ground external terminal disposed on an outer surface of the container, and electrically connected to the ground of the temperature detection circuit and the ground of the temperature control circuit.