A scooter type vehicle provides a pair of right and left frame members in the interior of a vehicle body cover so as to extend substantially horizontally between a head pipe and the front end of a seat. Right and left footrest plates are provided outside on the right and left of the vehicle body cover. An engine is provided between the right and left frame members with the cylinder axis of the cylinder block being provided so as to extend longitudinally, and the center axis of a crankshaft is provided so as to extend laterally and to be located above the upper surfaces of the right and left footrest plates as seen in a side view. A balancer shaft is located below the crankshaft, and the crankshaft and the balancer shaft are sandwiched and supported between the upper and lower case halves with their center axes being located on the joining surface.