Provided are a multiple-gate MOS (metal oxide semiconductor) transistor and a method of manufacturing the same. The transistor includes a single crystalline active region having a channel region having an upper portion of a streamlined shape (∩) obtained by patterning an upper portion of a bulk silicon substrate with an embossed pattern, and having a thicker and wider area than the channel region; a nitride layer formed at both side surfaces of the single crystalline active region to expose an upper portion of the single crystalline active region at a predetermined height; and a gate electrode formed to be overlaid with the exposed upper portion of the single crystalline active region of the channel region.