A straddled vehicle comprising: a fuel tank comprising or including a fuel filler port; a head pipe arranged in front of the fuel tank; a seat at least partially arranged behind the fuel tank; a storage box arranged below the seat and behind the fuel tank; a center cover arranged between the head pipe and the seat, the center cover having a downwardly recessed shape between the fuel tank and the head pipe; a power unit arranged below the fuel tank; a support attached to the fuel tank, the support being arranged around the fuel filler port; a hinge connected to the support; a cap that is movably attached to the support to an open position and a closed position via the hinge, opens the fuel filler port at the open position, and closes the fuel filler port at the closed position; an operating member attached to the cap, the operating member being operable by a rider or person; a slider attached to the cap, the slider being configured to move from an engaged position to a disengaged position with respect to the support by being pressed by the operating member; a solenoid comprising or including a lock member that is movable to a lock position at which the lock member locks a movement of the slider and a release position at which the lock member unlocks the slider; a sensor that detects the movement of the slider from the engaged position to the disengaged position; a receiver that receives a signal indicative of an identification code unique to a transmitter carried by a rider or person from the transmitter; and a controller that authenticates the identification code of the transmitter based on the signal received by the receiver wherein, when the identification code of the transmitter is appropriate, the controller authenticates the identification code of the transmitter; moves the lock member to the release position when the movement of the slider is detected by a signal from the sensor and the identification code of the transmitter is authenticated by the controller, and holds the lock member at the lock position responsive to the movement of the slider is detected but the identification code of the transmitter is not authenticated by the controller. a fuel tank comprising or including a fuel filler port; a head pipe arranged in front of the fuel tank; a seat at least partially arranged behind the fuel tank; a storage box arranged below the seat and behind the fuel tank; a center cover arranged between the head pipe and the seat, the center cover having a downwardly recessed shape between the fuel tank and the head pipe; a power unit arranged below the fuel tank; a support attached to the fuel tank, the support being arranged around the fuel filler port; a hinge connected to the support; a cap that is movably attached to the support to an open position and a closed position via the hinge, opens the fuel filler port at the open position, and closes the fuel filler port at the closed position; an operating member attached to the cap, the operating member being operable by a rider or person; a slider attached to the cap, the slider being configured to move from an engaged position to a disengaged position with respect to the support by being pressed by the operating member; a solenoid comprising or including a lock member that is movable to a lock position at which the lock member locks a movement of the slider and a release position at which the lock member unlocks the slider; a sensor that detects the movement of the slider from the engaged position to the disengaged position; a receiver that receives a signal indicative of an identification code unique to a transmitter carried by a rider or person from the transmitter; and a controller that authenticates the identification code of the transmitter based on the signal received by the receiver wherein, when the identification code of the transmitter is appropriate, the controller authenticates the identification code of the transmitter; moves the lock member to the release position when the movement of the slider is detected by a signal from the sensor and the identification code of the transmitter is authenticated by the controller, and holds the lock member at the lock position responsive to the movement of the slider is detected but the identification code of the transmitter is not authenticated by the controller.