A reel unit has a housing unit, a first lid, a second lid, and a rod-attachment portion. The housing unit has an accommodation space formed in the interior thereof that accommodates and supports a drive mechanism. The drive mechanism has a master gear non-rotatably coupled to a master gear shaft. The first lid is made of a metal and is fixedly coupled to the housing unit to interpose the master gear with the housing unit. The second lid is made of a synthetic resin and is fixedly coupled to the housing unit to close the accommodation space. The rod-attachment portion is formed integrally with the housing unit and can be mounted onto a fishing rod.