A fuel-tank assembly disposed in a space between a rear wheel and a seat of a straddle-type vehicle without impairing ride comfort, At least part of the seat is disposed above the rear wheel. A fuel tank has a bottom including a part inclined in a front-rear direction of the vehicle above the rear wheel and below the seat. A fuel pump unit for supplying fuel in the fuel tank to an engine has a body extending on and along the inclined part of the bottom in the fuel tank.