To secure the fastening strength while improving the workability in fitting a power unit to a car body side.

A press-in pin of a connecting member 1 is press fitted and connected in an inner cylinder 13 of a mount insulator 7 comprising an outer cylinder 11 fixed to a side member 5R, a support elastic body 12, and the inner cylinder 13. The connecting plate of the connecting member 11 is integrally provided with a rear block 21, a front block 22 and a separation block 23 positioned frontward of the front block 22 arranged at same-distant positions in the car body front/rear direction relative to the central axis of the pin, and the respective blocks are formed with bolt insertion holes. The bolt insertion hole of the separation block 23 has a positioning bolt 28 implanted projecting downward. A connecting part 29 of the unit side bracket 18 and the connecting plate 20 are connected together and firmly fixed in three points in a well balanced state by bolts and nuts.