Provided is a power supply circuit that supplies electric power to a biological signal measurement circuit configured to detect, with an electrode set in contact with a human body, a biological signal which is a weak electric signal emitted by the human body. The power supply circuit includes a capacitance element accumulating the electric power, and a circuit switch coupled between the capacitance element and an external power supply for supplying electric power to the capacitance element, and configured to switch, not through a state where the external power supply and the biological signal measurement circuit are electrically coupled, a first state where the capacitance element establishes electrical continuity with the external power supply and is enabled to be charged, and a second state where the capacitance element establishes electrical continuity with the biological signal measurement circuit and is enabled to supply power to the biological signal measurement circuit.
