A semiconductor integrated circuit includes a power line and a power supply circuitry. The power supply circuitry includes: a first power supply circuit operating on a first power supply voltage and having an output connected with the power line; and a second power supply circuit operating on a second power supply voltage higher than the first power supply voltage and having an output connected with the power line. The first power supply circuit is configured to drive the power line to a first preset, voltage. The second power supply circuit is configured to drive the power line to a second preset voltage lower than the first preset voltage. The second power supply circuit is configured not to decrease a third power supply voltage generated on the power line when the third power supply voltage is higher than the second preset voltage.