To provide a power supply circuit which can eliminate the need for inserting a protective resistor into a port by controlling the power supplies for a CPU core section and an I/F circuit section such that the power supply for the CPU core section starts up first and I/O initial setting from the CPU core section to the I/F circuit section is performed (input of a set up register is normally designated).

The power supply circuit includes a discharge circuit 131 which does not start power supply by discharging the output from a first power supply section 11, and a timing control section 13 which brings the discharge circuit 131 into discharging state until the voltage of a second power supply section 12 reaches a predetermined threshold, and stops discharge of the discharge circuit 131 when the voltage of the second power supply section 12 reaches the predetermined threshold and permits rising of voltage of the first power supply section 11.