To provide an ARQ controller that determines whether to start or repeat a retransmission request in a transmission system that employs an automatic error detection retransmission request system, the controller preventing unnecessary transmission of a retransmission request at a low cost with high accuracy without significantly changing the configuration.

The ARQ controller includes: a transmission quality evaluation means for evaluating transmission quality for each block received in the transmission system that employs the automatic error detection retransmission request system and including information individually; and a control means for regulating the retransmission request of a predetermined block to the transmission end of the predetermined block whose transmission quality evaluated by the transmission quality evaluation means is below a determinate threshold among the blocks.