An object of the present invention is to make it possible to easily fix a cover member to a reel unit of a spinning reel while exposure of a fixing member to a rear portion of the reel unit is reduced. A reel unit includes a reel body, a lid member, a reel unit protection member, and an intermediate member. The reel body includes an accommodation space that opens to a lateral side, a first insertion hole that is communicated with the accommodation space, and a second insertion hole that is disposed on the opposite side of the first insertion hole and is communicated with the accommodation space. The lid member is detachably/reattachably mounted to the reel body so as to cover the accommodation space. The reel unit protection member is mounted from backward so as to cover the reel body and the lid member, and includes a boss that passes through the first insertion hole from a rear portion of the reel body and protrudes toward the accommodation space. The intermediate member is non-movably provided in the reel body within the accommodation space, and retains a screw member fixed to a front end portion of the boss in the accommodation space.