A supercharger-equipped combustion engine includes a crankshaft extending in a widthwise direction of a vehicle supported by a crankcase and a supercharger disposed above the crankcase. Power from the crankshaft is transmitted through a supercharger transmission to the supercharger. A crankcase body has an opening formed to be opened at the right side in the widthwise direction, and at least a part of the opening is covered with a holder detachably mounted on the crankcase body. The supercharger transmission includes input and output shafts extending in the widthwise direction of the vehicle, and the input and output shafts are rotatably supported at first end portions thereof at the right side by first bearing portions formed in the holder and are rotatably supported at second end portions thereof at the left side by second bearing portions formed in a side wall of the crankcase body.