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