A handle assembly 1 for a spinning reel includes handle shafts 1a, and a handle arm 1b that is detachably mounted to a handle shaft 1a. The handle arm 1b has a through hole 1j formed in the base end thereof. A male threaded portion 80c of the handle shaft 1a is mounted in the through hole 1j, and the handle arm 1b is detachably installed on the handle shaft 1a by a nut member 90a. A cap member 90f that covers the entire nut member 90a is mounted to the outer periphery of the nut member 90a. A male threaded portion 90e is formed on the tip of the cap member 90f, and the cap member 90f is fixed to the nut member 90a by screwing the male threaded portion 90e to a female threaded portion 90d formed on a head portion of the nut member 90a.