An air cleaner is prevented from sucking mud etc., while a relatively large space is ensured in front of a seat, in an under bone type straddle type vehicle which has an area recessed downward in front of the seat. An air cleaner is disposed in the rear of a cylinder block of an engine. The air cleaner includes a cleaner case that is taller than it is broad and a lid that covers a top of the cleaner case. An intake pipe is positioned at a rear side of the lid. The intake pipe is disposed within a space surrounded by the seat and a forward descending portion of a seat front cover, and opens obliquely upward rearward. A labyrinth structure is formed above the intake pipe for preventing drops of water from entering the intake pipe from the seat.