A spinning reel allowing a fishing rod to be attached thereto, the spinning reel being configured to forwardly reel out a fishing line, the spinning reel comprising: a handle; a spool; a rotor being configured to wind the fishing line about the spool; an oscillating mechanism being configured to move the spool back and forth by rotation of the handle; a rotor drive mechanism being configured to rotate the rotor by the rotation of the handle; and a reel unit including: a fishing rod attachment leg allowing the fishing rod to be attached thereto, a chassis having a mechanism attachment space to accommodate the oscillating mechanism and the rotor drive mechanism, a lid member covering the mechanism attachment space, a reel unit guard having a tapered shape, the reel unit guard covering a rear side of the chassis and a rear side of the lid member, wherein the reel unit guard is fixed to the chassis in a first position close to the fishing rod attachment leg by a screw member, the reel unit guard is engaged with the chassis in a second position being farther away from the fishing rod attachment leg than from the first position, and a protruding portion protruding towards at least one of the chassis and the lid member from an inner lateral surface of the reel unit guard, the inner lateral surface being disposed on a side away from the fishing rod attachment leg, and a restriction portion being disposed on the lid member, the restriction portion being engaged with the protruding portion to restrict the reel unit guard from moving in a direction away from the fishing rod attachment leg, and the reel unit being provided with the fishing rod attachment leg disposed on either the chassis or the lid member, characterized in that the protruding portion has a first surface and a second surface disposed farther away from the fishing rod attachment leg than the first surface from the fishing rod attachment leg, and the protruding portion protrudes in a plate shape towards the lid member. a handle; a spool; a rotor being configured to wind the fishing line about the spool; an oscillating mechanism being configured to move the spool back and forth by rotation of the handle; a rotor drive mechanism being configured to rotate the rotor by the rotation of the handle; and a reel unit including: a fishing rod attachment leg allowing the fishing rod to be attached thereto, a chassis having a mechanism attachment space to accommodate the oscillating mechanism and the rotor drive mechanism, a lid member covering the mechanism attachment space, a reel unit guard having a tapered shape, the reel unit guard covering a rear side of the chassis and a rear side of the lid member, wherein the reel unit guard is fixed to the chassis in a first position close to the fishing rod attachment leg by a screw member, the reel unit guard is engaged with the chassis in a second position being farther away from the fishing rod attachment leg than from the first position, and a protruding portion protruding towards at least one of the chassis and the lid member from an inner lateral surface of the reel unit guard, the inner lateral surface being disposed on a side away from the fishing rod attachment leg, and a restriction portion being disposed on the lid member, the restriction portion being engaged with the protruding portion to restrict the reel unit guard from moving in a direction away from the fishing rod attachment leg, and the reel unit being provided with the fishing rod attachment leg disposed on either the chassis or the lid member, characterized in that the protruding portion has a first surface and a second surface disposed farther away from the fishing rod attachment leg than the first surface from the fishing rod attachment leg, and the protruding portion protrudes in a plate shape towards the lid member. a fishing rod attachment leg allowing the fishing rod to be attached thereto, a chassis having a mechanism attachment space to accommodate the oscillating mechanism and the rotor drive mechanism, a lid member covering the mechanism attachment space, a reel unit guard having a tapered shape, the reel unit guard covering a rear side of the chassis and a rear side of the lid member, wherein the reel unit guard is fixed to the chassis in a first position close to the fishing rod attachment leg by a screw member, the reel unit guard is engaged with the chassis in a second position being farther away from the fishing rod attachment leg than from the first position, and a protruding portion protruding towards at least one of the chassis and the lid member from an inner lateral surface of the reel unit guard, the inner lateral surface being disposed on a side away from the fishing rod attachment leg, and a restriction portion being disposed on the lid member, the restriction portion being engaged with the protruding portion to restrict the reel unit guard from moving in a direction away from the fishing rod attachment leg, and the reel unit being provided with the fishing rod attachment leg disposed on either the chassis or the lid member, characterized in that the protruding portion has a first surface and a second surface disposed farther away from the fishing rod attachment leg than the first surface from the fishing rod attachment leg, and the protruding portion protrudes in a plate shape towards the lid member.