The present invention provides a scheduling method in a wireless personal area network (WPAN) system and a device therefor. Specifically, a method for allocating a guaranteed time slot (GTS) in a WPNA system comprises the steps of: receiving a GTS request command for requesting periodic GTS allocation from a device; and transmitting a beacon frame which includes periodic GTS allocation information to the device, wherein a GTS allocation interval is determined by GTS interval information included in the GTS request command, and an allocated periodic GTS expires if data or an acknowledgement (ACK) frame is not transmitted from the device within a section determined by the GTS allocation interval.