A bottom frame (50) which constitutes a bottom surface of a casing (40) is divided into a main bottom frame (51) where a first compressor (11) is to be provided and a sub bottom frame (55) where a second compressor (21) is to be provided. The main bottom frame (51) is further divided into a first bottom frame (52) and a second bottom frame (53). The first compressor (11) is to be provided on the first bottom frame (52). A refrigerant circuit component (47) to be replaced or added in accordance with a capability or a function is to be provided on the second bottom frame (53).