According to example embodiments, an optical measurement apparatus may include: a station configured to support a measurement target; an image acquisition unit configured to acquire a one-dimensional (1D) line image of the measurement target; a driver configured to move the station and the image acquisition unit; and a controller. The controller may be configured to control the driver and the image acquisition unit to acquire a plurality of 1D line images of the measurement target while varying a distance between the image acquisition unit and the measurement target to generate a two-dimensional (2D) scan image from combining the plurality of 1D line images; and to detect a pattern of the measurement target based on comparing a plurality of 2D reference images and the 2D scan image. The optical measurement apparatus may measure critical dimensions of non-repeating ultrafine patterns at high speed.