The reel unit has a first side plate made of a magnesium alloy and a first side cover made of an aluminum alloy mounted to a side of the first side plate. The first side plate has an opening and a plurality of plate-like members made of an aluminum alloy mounted to the first side plate around the opening. The first side cover has an opening, and a brake case made of an aluminum alloy turnably mounted in the opening. Aluminum alloy protrusions are formed on an outer peripheral side of the brake case. The first side cover is secured to the first side plat by causing the protrusions formed on the brake case to engage in a bayonet fashion with the plate-like members separately attached to the first side plate.