More rapid and effective communication is performed between mobile units that cannot communicate directly due to impediments to communication that block signals.A mobile unit communication apparatus (1), including a wireless transceiver (9), is provided at a mobile unit. At the mobile unit communication apparatus (1), a surrounding object detection unit (6) detects objects surrounding the mobile unit. The surrounding communication impediment detection unit (7) detects a likelihood of an impediment to communication in the surroundings of the mobile unit from conditions for surrounding objects detected by the surrounding object detection unit (6). A relay communication unit (16) transmits information received by the wireless transceiver (9) from the wireless transceiver (9). A relay wait time setting unit (15) sets a time until information received by the wireless transceiver (9) is transmitted by the relay communication unit (16) from the wireless transceiver (9) longer for a larger likelihood of an impediment to communication detected by the surrounding communication impediment detection unit (7).