A semiconductor integrated circuit includes a scan enable (SE) inverter and a clock (CK) inverter on a substrate, a first multiplex part, and a second multiplex part. The SE inverter and the CK inverter are aligned in a first direction. The first multiplex part includes a first wiring and a first transistor, the first wiring is connected to a power supply voltage part of the SE inverter, and the first wiring and the first transistor share a source region contacting the first wiring. The second multiplex part includes a second wiring and a second transistor, the second wiring is connected to a power supply voltage part of the CK inverter, and the second wiring and the second transistor share a source region contacting the second wiring. The SE inverter and the CK inverter are aligned in a first direction to each other.