To improve a degree of freedom of layout of engine constituent parts achieve efficient wiring, and improve resistance against vibration by fixing a sensor mounting holder as a single part which is made of a vibration control material and holds a plurality of sensors on an engine.

A sensor mounting holder 34 made of a vibration control material is a single part substantially in the shape of a box and consists mainly of a first hold part 34a which holds an atmospheric pressure detection sensor 30, a second hold part 34b which holds a suction air temperature detection sensor 28, and a mounting piece part 34c which has a bolt insertion hole 34c1. The atmospheric pressure detection sensor 30 has a detection port 30a which protrudes downward in a lower wall thereof, and the detection port 34a is inserted and fixed from a rear open side in the first hold part 34a in a condition in which it is escaped in a long hole. The suction air temperature detection sensor 28 is inserted in the second hold part 34b from the left side to the right side, and a lead wire 28a is held in a lead wire hold part 34e after it is folded back on the left side of the second hold part 34b. The sensor mounting holder 34 is fixed on a side wall of a surge tank.