A wiring aggregation apparatus includes at least one subunit. The subunit includes: an input/output module to output, to a control module, a first serial signal obtained by performing parallel-serial conversion on plural pieces of contact information collected from devices, and to output, to a corresponding device, each of plural pieces of contact information obtained by performing serial-parallel conversion on a second serial signal acquired from the control module; and the control module to generate a transmit frame by arranging the first serial signal acquired from the input/output module at a defined frame position, to transmit the generated transmit frame to another wiring aggregation apparatus, to extract the second serial signal arranged at a defined frame position from a receive frame acquired from the another wiring aggregation apparatus, and to output the extracted second serial signal to the corresponding input/output module.