A first main frame segment 62 extends rearwardly from a head pipe 4, a second main frame segment 64 pivotally supports a swingarm 12, and an engine casing EC is disposed between the head pipe 4 and the swingarm 12. The engine casing EC includes a crankcase section 28, a cylinder part 30, a cylinder head part 32 and a transmission casing section 34. The first main frame segment 64 includes a first mount portion 56, which is connected with a front portion of the cylinder part 30, and a second mount portion 58 which is connected with a rear portion of the cylinder head part 32. The second main frame segment 64 includes a third mount portion 60 which is connected with a rear portion of the transmission casing section 34.