PURPOSE: To make a partial high-speed operation possible by boosting a supply voltage for a part where high-speed operation is required in the integrated circuit using CMOS.

CONSTITUTION: For the purpose of supplying signal S1 from VCC system circuit 1, where low voltage VCC is supplied, to high-speed operation circuit part 3 where high-speed operation is required, signal S1 is applied to level shifter circuit 2 and is applied to circuit part 3 as level-shifted signal S2. High voltage VDD boosted by boosting unit 4 is applied to level shifter circuit 2 and high-speed operation circuit part 3. Output signal S3 of high-speed operation circuit part 3 is applied to another VCC system circuit 1'.