A lubricating oil passage structure for a bearing of an oil cooled rotating machine includes a bearing (114) arranged in the center of a bracket (111) to rotatably support a rotary shaft (101). Protruding ribs (116, 117, 117a) are spirally arranged on the inner surface of the bracket (111). Also, a bearing rib (112) having an oil passage groove (113) for supplying the bearing (114) with lubricating oil is formed on the inner surface of the bracket (111). An upper projection hole (110) is formed in the upper portion of the bracket (111) for introducing the lubricating oil. The protruding ribs located on the right and left of the upper projection hole (110) in the circumferential direction are the upper protruding ribs (116) which function as guides for guiding the lubricating oil to the bearing rib. Therefore, the lubricating oil passage structure constitutes a structure that captures the lubricating oil and guides the oil to the bearing (114) without reducing the support rigidity of the bearing, while also constituting a rib structure capable of both improving the support rigidity of the bearing and inhibiting failure of the bearing (114).