A fuel supply apparatus capable of following the positional variations of the bottom side of a fuel tank through a simple construction and improved in terms of ease of assembly in the fuel tank. The apparatus includes a fuel pump body in which a filter-integrated pump in which a fuel pump and a fuel filter are integrally formed is integrally accommodated in a fuel reservoir having a bottom capable of coming into abutment with a bottom side of the fuel tank, and causes the fuel pump body to travel to follow the variations of the bottom side of the fuel tank so as to be placed in abutment with the bottom side of the fuel tank, by means of an urging force generated on the basis of the pressure of the fuel inside the fuel pump body.