PURPOSE: To get rid of any possibility that water might be splashed to a belt by setting up an oil pump in space between a compressor and an oil pan, and connecting a crankshaft, a compressor and the oil pump together through a belt rotation transmitting means.

CONSTITUTION: An air-conditioning compressor 11 is set up in the upper part aslant in the lower part of a cylinder block 1b. In addition, a power steering oil pump 12 is installed in space between this compressor 11 and a first oil pan 1c. A recess 13 for setting up this oil pump 12 is formed in an upper part of the first oil pan 1c. Next, the oil pump 12 is attached to a position adjustable mounting means 14. A belt 18 is wound on a crank pulley 15, a compressor pulley 16 and a pump pulley 17, thereby constituting a second belt rotation transmitting means 19 which drives the compressor 11 and the oil pump 13. Thus, any fear of splashing water to the belt is brought to nothing.