A seatbelt reel-in device comprising: a reel-in rotating body for freely reeling and unreeling a seatbelt for restraining a small child sitting in a child seat, the reel-in rotating body being urged in a direction to reel the seatbelt by a reel-in spring; a rotation lock mechanism for disabling rotation of the reel-in rotating body, the rotation lock mechanism being capable of switching back and forth between a locking state for disabling rotation of the reel-in rotating body and an unlocking state for permitting rotation of the reel-in rotating body, the rotation lock mechanism comprises a lock gear mounted in the reel-in rotating body, a lock pawl which releasably engages with the lock gear to disable rotation of the reel-in rotating body, and a lock member for locking the lock pawl in engagement with the lock gear, the lock member being free to switch back and forth between a locking state for locking the lock pawl in engagement with the lock gear and an unlocking state for separating the lock pawl from the lock gear; a lock operation tool for switching the rotation lock mechanism back and forth between the locking state and the unlocking state; an inhibiting mechanism having an inhibiting member for inhibiting the lock member of the rotation lock mechanism from switching from the locking state to the unlocking state, the inhibiting member of the inhibiting mechanism being supported so as to be moveably switching back and forth between an inhibiting position to inhibit the lock member of the rotation lock mechanism from switching to the unlocking state and a permitting position to allow the lock member of the rotation lock mechanism to switch to the unlocking state; and wherein an inhibiting spring is provided to urge the inhibiting member toward the inhibiting position; and an inhibition operation tool for switching the inhibiting mechanism back and forth between the inhibiting state and the permitting state; wherein the inhibiting member can be automatically returned to the inhibiting position under the urgence of the inhibiting spring by returning the lock member to the locking state. a reel-in rotating body for freely reeling and unreeling a seatbelt for restraining a small child sitting in a child seat, the reel-in rotating body being urged in a direction to reel the seatbelt by a reel-in spring; a rotation lock mechanism for disabling rotation of the reel-in rotating body, the rotation lock mechanism being capable of switching back and forth between a locking state for disabling rotation of the reel-in rotating body and an unlocking state for permitting rotation of the reel-in rotating body, the rotation lock mechanism comprises a lock gear mounted in the reel-in rotating body, a lock pawl which releasably engages with the lock gear to disable rotation of the reel-in rotating body, and a lock member for locking the lock pawl in engagement with the lock gear, the lock member being free to switch back and forth between a locking state for locking the lock pawl in engagement with the lock gear and an unlocking state for separating the lock pawl from the lock gear; a lock operation tool for switching the rotation lock mechanism back and forth between the locking state and the unlocking state; an inhibiting mechanism having an inhibiting member for inhibiting the lock member of the rotation lock mechanism from switching from the locking state to the unlocking state, the inhibiting member of the inhibiting mechanism being supported so as to be moveably switching back and forth between an inhibiting position to inhibit the lock member of the rotation lock mechanism from switching to the unlocking state and a permitting position to allow the lock member of the rotation lock mechanism to switch to the unlocking state; and wherein an inhibiting spring is provided to urge the inhibiting member toward the inhibiting position; and an inhibition operation tool for switching the inhibiting mechanism back and forth between the inhibiting state and the permitting state; wherein the inhibiting member can be automatically returned to the inhibiting position under the urgence of the inhibiting spring by returning the lock member to the locking state.