A projector includes a casing, a light source disposed in the casing and capable of providing an illumination beam, a light valve disposed in the casing and capable of converting the illumination beam into an image beam, a lens disposed in the casing and adapted to project the image beam, and the lens collar module. The lens collar module includes a fitting part and a lens collar. The fitting part is formed on the casing, and has a fitting opening and a first bump. The lens collar has a fitting periphery and a second bump. The fitting periphery is fitted to the fitting opening, the lens collar is adapted to be rotated and translated relative to the casing along an axial direction. Engagement of the first bump and the second bump limits rotation and translation of the lens collar relative to the casing along the axial direction.