A circuit block including standard cells (1) arranged therein is provided with switch cells (20) capable of switching between electrical connection and disconnection between power supply lines (3) extending in an X-direction and power supply straps (11) extending in a Y-direction. Each of the power supply straps (11) is provided with a single switch cell (20) arranged every M sets of power supply lines (3) (M is an integer of 3 or more). In the Y-direction, the switch cells (20) are arranged at different positions in the power supply straps (11) adjacent to each other, and are arranged at the same position every M power supply straps (11) in the X-direction.