The invention provides a driving apparatus for a tire building drum which can reduce load when the drum is rotating, which enables stable expanding and contracting operations and in which a center shaft portion (2) of the building drum (D) is made up of a cylindrical outer shaft (3) and an inner threaded shaft (4), the driving apparatus including a cylindrical outer shaft (13) which is coupled to the outer shaft (3), an inner shaft (14) coupled to the threaded shaft (4), a first motor (15) which is a rotational driving means coupled to the outer shaft (13) for rotating the drum, and a second motor (20) which is a rotational driving means coupled to the inner shaft (14) via a clutch (21) in such a manner as to be engaged with and disengaged from the inner shaft for expanding or contracting the drum, wherein by switching the clutch (21), when the drum is rotating, the second motor (20) is held out of engagement with the inner shaft (14), while when the drum is expanded or contracted, the second motor (20) is held in engagement with the inner shaft (14).