A lens module includes a lens barrel, and a lens group having a first and second lenses. An image side surface of a first barrel wall includes a first planar surface, a first oblique surface obliquely extending from the first planar surface, and a second planar surface extending from the first oblique surface. An object side surface of a peripheral portion of the first lens includes a second oblique surface attached to the first oblique surface and a fourth planar surface attached to the second planar surface. An image side surface of the peripheral portion of the first lens includes a fifth planar surface, a third oblique surface obliquely extending from the fifth planar surface, and a sixth planar surface extending from the third oblique surface towards the optical axis. An object side surface of the second lens includes a seventh planar surface and a fourth oblique surface.