To provide an electrical component cooling structure for an outboard engine for efficiently cooling electrical component in a high-temperature atmosphere while keeping the engine at a proper temperature and requiring a less number of parts to form a compact, low-cost cooling water passage.

The outboard engine 1 has an engine control unit 30 with built-in electronic parts 44. The engine control unit 30 has an electrical component case 37 for storing the electronic parts 44, and the electrical component case 37 has an electrical component cooling water passage 38 integrally formed near the electronic parts 44 and connection portions 38a, 38b integrally formed via which a cooling water supply hose 31 and a cooling water drain hose 33 are connected. The electrical component cooling water passage 38 is formed along the direction almost the same as the direction of drawing the electrical component case 37 for supplying part of a cooling water to be supplied to the engine 3 to the electrical component cooling water passage 38.