The present invention relates to a wireless connection system, and in particular, relates to methods of retransmitting data in a machine-to-machine communication system, methods of managing the data, and devices for supporting machine-to-machine communication. As one aspect of the present invention, the method of retransmitting data in the wireless connection system supporting the machine-to-machine communication may include: allocating a data slot for retransmitting data from a first machine, from among two or more peer machines, by transmitting a transmit request message to a second machine; receiving a transmit response message transmitted form the second machine in response to the transmit request message; and retransmitting data to the second machine through the allocated data slot.