A needle threader for a sewing machine includes a threading mechanism including a threading hook mounted on a lower end of a threading shaft and a thread guide member. The threading hook and the thread guide member are movable among a thread guide preparation position where the threading hook and the thread guide member are located near a height position of a needle clamp, a threading operation position where a threading operation is carried out with the threading hook being level with an eye of a needle, and a retreat position which is located above the thread guide preparation position and to which the threading hook and the thread guide member are retreated. A vertical moving mechanism moves the threading shaft vertically so that the threading mechanism is moved among the thread guide preparation position, the threading operation position and the retreat position.