It is possible to simplify an internal structure of a silencer and it is possible to improve silencing performance while suppressing the increase of the size of the silencer. An exhaust pipe structure is constituted by an exhaust pipe (45) which is connected to an engine (4), and a silencer (43) which is disposed under the engine. A silencer inlet (43a) through which exhaust gas is introduced into the silencer is provided in the silencer and at the rear of a vehicle body. The exhaust pipe has a rear portion reversal pipe (62) by which a direction of an exhaust stream flowing rearward is reversed into a frontward direction. A downstream end side of the rear portion reversal pipe is connected to the silencer inlet. A silencer outlet (43b) through which exhaust gas is discharged from the silencer is provided in the silencer. The silencer outlet is provided at the front of the vehicle body. Thus, exhaust gas can flow inside the silencer unidirectionally from the rear toward the front.