A switching loss is reduced by reducing a deviation from the operational principle of zero-volt switching (ZVS). A semiconductor integrated circuit includes high-side switch elements Q11 and Q12, a low-side switch element Q2, and a controller CNT. A decoupling capacitance Cin is coupled between one end of a high-side element and an earth potential, and the high-side element includes the first and second transistors Q11 and Q12 coupled in parallel. In changing the high-side elements from an on-state to an off-state, CNT controls Q12 from an on-state to an off-state by delaying Q12 relative to Q11. Q11 and Q12 are divided into a plurality of parts inside a semiconductor chip Chip 1, a plurality of partial first transistors formed by dividing Q11 and a plurality of partial second transistors formed by dividing Q12 are alternately arranged in an arrangement direction of Q11 and Q12, inside the semiconductor chip Chip 1.