A turbomachine of the present disclosure includes a rotating shaft, an impeller, a bearing, and a casing. The casing is arranged around the impeller in a circumferential direction of the rotating shaft. A volute is defined in the casing as a passage of a working fluid that is compressed or expanded by rotation of the impeller. The casing includes one or more ribs. The one or more ribs are arranged only in a diagonal area, or the one or more ribs are a plurality of ribs and a degree of reinforcement of the diagonal area by the plurality of ribs is larger than a degree of reinforcement of a tongue portion area by the plurality of ribs.