An engine of a straddle-type vehicle includes a seal between a surrounding wall and a pipe. A cylinder head includes a first surrounding wall portion and a second surrounding wall portion. One end of the pipe is pressed in against the first surrounding wall portion. The second surrounding wall portion is located more distant from an attachment portion than the first surrounding wall portion is, and has an inner diameter larger than that of the first surrounding wall portion. The pipe includes an annular projection. The annular projection projects from the outer periphery of the pipe, and divides a space defined by the outer periphery of the pipe and the inner periphery of the second surrounding wall portion into subspaces arranged in an axial direction of the pipe when the one end of the pipe is pressed in against the first surrounding wall portion.