A light scanning device equipped with a housing that houses lenses, a rotating multifaceted mirror, and a motor for driving rotation of the rotating multifaceted mirror, and has a bearing section for rotatably supporting the rotating shaft of the motor. The bearing section has a first fitting section of circular shape rotatably supporting the entire peripheral face of the rotating shaft, a second fitting section extending towards an outer edge of the housing from the peripheral edge of the first fitting section, and having an arcuate face formed to identical radial length as the first fitting section, and a heat-radiating section adjacent to the second fitting section in the circumferential direction, formed by a slot cut out in a predetermined direction, and adapted to expose a portion of the outside peripheral face of the rotating shaft through the housing.