Rotary machine unit, compressor, and refrigeration device

A rotary machine unit comprising:

• a casing having a tubular barrel;
• a stator core fixed to an inner peripheral surface of the tubular barrel;
• and
• a first member provided between the inner peripheral surface of the tubular barrel and an outer peripheral surface of the stator core,
• the tubular barrel including a barrel body and a welded portion that connects circumferentially opposing ends of the barrel body,
• the tubular barrel having a concave portion formed in the inner peripheral surface of the tubular barrel, the concave portion being a groove formed in the welded portion,
• the first member being provided between the concave portion and the outer peripheral surface of the stator core, and
• the first member being made of a material having a lower Young's modulus than a material forming the tubular barrel and a material forming the stator core.