Abstract: A packet retransmission control system has: a network control block configured to perform packet retransmission control in an upper layer; and a packet retransmission control block configured to perform packet retransmission control with a shorter retransmission timeout than the upper layer in a lower layer that is lower than the upper layer. If the network control block receives a duplicate acknowledge packet being an acknowledge packet notifying a same sequence number for a predetermined number of times, the network control block performs packet retransmission. The packet retransmission control block determines whether or not retransmission of a same packet is performed earlier in the upper layer than in the lower layer. If retransmission of the same packet is performed earlier in the upper layer than in the lower layer, the packet retransmission control block prohibits retransmission of the same packet in the lower layer.