Nishi-ku is one of seven wards of Hamamatsu, Shizuoka, Japan, located in the southwest corner of the city. It is bordered by Naka-ku, Kita-ku, Minami-ku, and the city of Kosai. The 3rd largest ward of Hamamatsu in terms of area, much of the ward is still rural, with farms and rice fields.
Nishi-ku was created on April 1, 2007 when Hamamatsu became a city designated by government ordinance.
Nishi-ku is served by Maisaka Station and Bentenjima Station on the Tōkaidō Main Line railway.