FUEL SUPPLY DEVICE

A fuel supply device, which is mounted on a fuel tank, includes a lid member that covers an opening of the fuel tank, arm members mounted on the lid member, and a component mounted on the lid member via the arm members. The arm members and the component have an engaging structure which engages each other by elastic deformation of the arm members. The arm members are made of a resin material having a higher elastic modulus than the resin material forming the lid member.