A rotary machine includes an impeller. The impeller includes a discoid disk that rotates about an axis line, blades disposed circumferentially at intervals on a surface of the disk facing one side in a direction of the axial line and that form a flow path therebetween that extends radially outward from one side in the direction of the axial line, and a cover that covers the blades from a radially outer side. The rotary machine further includes a casing that covers the impeller from the radially outer side and forms a gap between the casing and an outer surface of the cover; a seal portion provided in the gap; and a lid member.