A straddled vehicle comprising: a main seat configured for a driver to sit on; a tandem seat disposed rearward of the main seat and configured for a co-rider to sit on; a seat frame being located below the main seat and the tandem seat with regard to an up-down direction of the vehicle to support the main seat and the tandem seat; a seat lock bracket attached to the seat frame and disposed near a rear end portion of the main seat; a main seat lock mechanism configured to secure the main seat to the seat frame in a detachable manner; and a tandem seat lock mechanism configured to secure the tandem seat to the seat frame in a detachable manner, the tandem seat lock mechanism being configured to be manipulable with a key, wherein, the main seat lock mechanism is attached to the seat lock bracket; the main seat includes a first engaging portion disposed on a back face of the main seat; the main seat lock mechanism includes a manipulable portion configured to be manipulated with a finger of the driver, and a second engaging portion configured to engage with the first engaging portion; the straddled vehicle further includes a manipulation restricting member configured to restrict manipulation of the manipulable portion of the main seat lock mechanism, the manipulation restricting member being provided as a separate piece from the tandem seat and mounted to the seat lock bracket in a detachable manner; a portion of the manipulation restricting member is covered by the tandem seat in an upper plan view of the vehicle; and the manipulation restricting member includes a recess formed in the portion that is covered by the tandem seat in an upper plan view of the vehicle, the recess having a depth extending along the up-down direction of the vehicle, characterized in that the tandem seat includes a downward-protruding protrusion with regard to the up-down direction of the vehicle, and/or the seat lock bracket includes an upward-protruding protrusion with regard to the up-down direction of the vehicle; and the protrusion of the tandem seat and/or the protrusion of the seat lock bracket are inserted in the recess of the manipulation restricting member. a main seat configured for a driver to sit on; a tandem seat disposed rearward of the main seat and configured for a co-rider to sit on; a seat frame being located below the main seat and the tandem seat with regard to an up-down direction of the vehicle to support the main seat and the tandem seat; a seat lock bracket attached to the seat frame and disposed near a rear end portion of the main seat; a main seat lock mechanism configured to secure the main seat to the seat frame in a detachable manner; and a tandem seat lock mechanism configured to secure the tandem seat to the seat frame in a detachable manner, the tandem seat lock mechanism being configured to be manipulable with a key, wherein, the main seat lock mechanism is attached to the seat lock bracket; the main seat includes a first engaging portion disposed on a back face of the main seat; the main seat lock mechanism includes a manipulable portion configured to be manipulated with a finger of the driver, and a second engaging portion configured to engage with the first engaging portion; the straddled vehicle further includes a manipulation restricting member configured to restrict manipulation of the manipulable portion of the main seat lock mechanism, the manipulation restricting member being provided as a separate piece from the tandem seat and mounted to the seat lock bracket in a detachable manner; a portion of the manipulation restricting member is covered by the tandem seat in an upper plan view of the vehicle; and the manipulation restricting member includes a recess formed in the portion that is covered by the tandem seat in an upper plan view of the vehicle, the recess having a depth extending along the up-down direction of the vehicle, characterized in that the tandem seat includes a downward-protruding protrusion with regard to the up-down direction of the vehicle, and/or the seat lock bracket includes an upward-protruding protrusion with regard to the up-down direction of the vehicle; and the protrusion of the tandem seat and/or the protrusion of the seat lock bracket are inserted in the recess of the manipulation restricting member.