An automatic homing apparatus of a rotatable module applied to a foldable device. The foldable device includes a first casing and a second casing. The automatic homing apparatus includes a fastener, a pivot, and a transmission mechanism. The fastener is for fastening the first casing and the second casing. The pivot is for pivotally connecting the rotatable module to the first casing. The transmission mechanism is disposed at one end of the pivot. When the first casing is fastened to the second casing, the transmission mechanism is actuated by the fastener so that the pivot drives the rotatable module to turn for homing.