PURPOSE: To improve the connection of a crank case composed of two separated cases by fastening a support part between both cases and fitting a car body with an engine through this support part.

CONSTITUTION: A crank case 11 is composed of two separated type cases 12 and 13 to be separated to an upper and a lower part essentially in the central part. When this upper case 12 is combined with the lower one 13, a bolt 19 is inserted from under the lower case 13 for screwing and fastening the upper case 12. On each case 12 and 13 near the almost central part of the backside of the crank case 11, stay fixing faces 32 and 33 almost similar to stay fixing faces 20 and 21 are provided for fixing a stay 34. On a slab 35 of the stay 34, holes 38 and 38 corresponding to a bracket fixing hole 10' are opened, and an engine E is supported on a car body 1 with stays 22, 26, and 34 between.