A pyroelectric infrared body sensing switch circuit comprises an amplification circuit, a delay unit, an execution unit, and an infrared detection circuit comprising one or more pyroelectric infrared detection elements. A power unit comprises first and second power circuits. Each of the first and second power circuits receives AC power and supplies DC power through RC voltage reduction, full-wave rectification, filtration, and voltage stabilization. The first power circuit supplies power to the execution unit and the second power circuit supplies power to the infrared detection circuit, the amplification circuit, and the delay unit. A signal outputted from the infrared detection circuit is inputted to the amplification circuit. A signal outputted from the amplification circuit controls the activation of the delay unit. A signal output from the delay unit controls the execution unit. The signal outputted from the infrared detection circuit comprises superposed output signals from the pyroelectric infrared detection elements.