A lens assembly of a camera module mounted in a small portable device includes a body receiving at least one lens and having a hole at one side, a screw member inserted in the hole in a direction substantially parallel to an optical axis, a support boss provided at the other side of the body and including a coupling hole formed in a direction substantially parallel to the optical axis, and a guide groove formed at one side of a side surface of the support boss, a shaft coupled with the coupling hole of the support boss and guiding a movement of the body, and a guide member having one side elastically and tightly attached to the screw member and moved by rotation of the screw member, and the other side coupled with the shaft to be movable along the guide groove and moving the body along the optical axis.