In a fuel supply device including a regulator and float-type level sensor, a fitting tube is formed integrally with an upper housing, a fuel pump being retained between the upper and lower housings. An outer periphery of a base part of the regulator is fitted into the tube. A regulator retaining member is formed as a separate member from the upper housing and retains the regulator in cooperation with the tube. The tube and the retaining member are joined via a snap-fit join part provided on fitting parts therebetween. The snap-fit join part is formed by engaging a projecting portion or a recess part, formed on an elastic piece provided on one of the fitting parts between the retaining member and the tube, with the recess part or the projecting portion formed on the other fitting part. A sensor support arm is molded as a unit with the retaining member.