A driving apparatus of a tire forming drum in which rotation of left-hand and right-hand bead locking mechanisms and movement of these bead locking mechanisms in directions of approaching and separating from each other can be effected simultaneously. A state of a main shaft and an inner shaft of the driving apparatus of the tire forming drum can be switched between a connected state and a non-connected state by a clutch. The main shaft and the inner shaft are both connected to a differential gear unit. An encoder is fixed to the differential gear unit and can detect the rotational difference between the inner shaft and the main shaft. Connected to the inner shaft are a distance-between-beads changing motor and a distance-between-beads fixing brake. Mounted to the main shaft are a main shaft rotating motor and a disc brake. A left-hand screw and a right-hand screw are formed on the inner shaft and the left-hand and right-hand bead locking mechanisms are screwed on the left-hand screw and the right-hand screw, respectively.