A work machine includes a first cooling unit that protrudes from a first wall surface at a first position of a main flow path and defines a first opening portion between the second wall surface and the first cooling unit; a second cooling unit that protrudes from the second wall surface on a downstream side of the first position in the flow path direction of the main flow path, defines a second opening portion between the first wall surface and the second cooling unit and partly overlaps with the first cooling unit when viewed from the flow path direction; and partition member that defines a first section flow path having the first cooling unit as an inlet and the second opening portion as an outlet and a second section flow path having the first opening portion as an inlet and the second cooling unit as an outlet.