A refrigeration unit body (31) is mounted to a trailer (20). The refrigeration unit body (31) includes a refrigerant circuit (40), an engine (50) and an electric generator (51). The refrigeration unit body (31) has a condensation side passage (70) formed from the front surface of the refrigeration unit body (31) to the top thereof. In the condensation side passage (70), a condenser (42) and an electrical component box (54) are disposed in series with condenser fans (44) for the condenser (42) and a radiator (55) in order from upstream to downstream of air flow. In addition, the refrigeration unit body (31) has an evaporation side passage (71) formed therein. The condenser fans (44) in the condensation side passage (70) and evaporation fans in the evaporation side passage are disposed alternately in the width direction of the refrigeration unit body (31).