A data slot allocation method allowing a plurality of devices in a wireless personal area network (WPAN) to satisfy the required QoS condition for the data stream transmission. The method includes allocating a specific number of data slots of a superframe to the plurality of the devices based on the QoS information; additionally allocating a certain number of data slots to a first device when the first device transmitting a data stream is allocated data slots less than a number of required data slots for the data stream transmission; and reserving the additional data slots for the first device by reducing a number of data slots to be allocated to the other devices, excluding the first device. Accordingly, the data slots can be fairly distributed to the devices.