PURPOSE: To highly integrate by providing a first semiconductor substrate made of silicon single crystal and a second semiconductor substrate made of compound semiconductor, and driving a circuit block of the second substrate or an element by a transistor of the first substrate or a circuit having the transistor.

CONSTITUTION: A driving circuit B such as an emitter follower having a bipolar transistor formed on a silicon substrate is provided between unit blocks A of circuits such as differential circuits formed of a GaAs-MESFET formed on Ga, As substrate. In this case, a level conversion circuit is provided at an input or output stage of the block A or the circuit B. An area occupied by the block A is increased larger than that occupied by the circuit B. Further, a capacity, a resistor of passive elements are formed in the block A region to reduce a capacity, a parasitic capacity of the junction. Thus, a speed acceleration, a high integration, low power consumption can be performed.