A wireless relay apparatus capable of high-quality transmission of data includes a wireless control unit and a data link communication unit wirelessly receiving and transmitting data. The wireless relay apparatus also includes a congestion status determining unit determining whether a congestion caused by radio wave interference occurs in the wireless relay apparatus, and includes a data flow determining unit identifying a flow of data transmitted and received by the wireless relay apparatus and determining whether the flows intersect in the wireless relay apparatus, when the congestion status determining unit determines that there is a congestion. In addition, the wireless relay apparatus includes a transmission parameter adjustment unit adjusting transmission characteristics of a type according to a result of the determination by the data flow determining unit, from among types of transmission characteristics of radio used in at least one of the wireless control unit and the communication apparatuses.