A fuel supply device for an engine is provided in which a throttle body is provided with an electrically operated fuel pump, wherein a base member integrally having a base portion that extends in the vertical direction on one side of the throttle body and a housing tube portion that is formed into a bottomed tube shape having an end wall communicating with the base portion is linked integrally to a body, a pump housing case that forms a fuel storage chamber is formed from the housing tube portion and a bottomed tubular housing cover joined to the housing tube portion via a seal member and is disposed beneath the body, and a vapor discharge path for discharging vapor generated in a fuel storage chamber is formed in the base portion so as to extend in the vertical direction and communicate with the fuel storage chamber.