A master gear shaft (10) of a spinning reel has a through-hole (10a) having a rectangular cross-section formed on the inner periphery of the master gear shaft. A handle shaft (7c) has a head that interlocks with the right end of the master gear shaft, a trunk (7e) which extends from the head (7d) and is non-rotatively inserted into the through-hole, and a first threaded portion (8a, 8c) having a male screw projecting from the tip of the trunk. A handle arm has a boss (7f) for interlocking with the left end of the master gear shaft, a second threaded portion, which is a female screw threaded portion that engages with the first threaded portion and is provided on the boss, and an arm that extends from the boss in a direction interlocking with the master gear shaft. The handle assembly prevents a handle shaft from loosening from a master gear shaft in a spinning reel.