A projector includes a color wheel module and an optical engine. The color wheel module includes a rotation device, a mount, a color wheel, and an optical sensor. The color wheel is fixed on a rotary part of the rotation device. The rotation device and the optical sensor are fixed on the mount. The mount has an anti-dust structure includes a curved surface that is opposite to a rotary surface of the rotary part and extends in a rotation direction of the rotary part. The curved surface and the optical sensor are arranged sequentially in the rotation direction. Either by shortening a distance between the curved surface and the rotary surface or by a guiding slot that is disposed beside or lower than the curved surface, dust deposited on the optical sensor can be reduced effectively.