A lens barrel assembly, which has improved shock resistance and quickly resumes normal operation when external shock is applied, includes a first barrel including an elastic moving pin which protrudes toward a second barrel and elastically deforms. The second barrel includes a first guide groove into which the elastic moving pin is inserted and which extends obliquely in a circumferential direction to guide a movement of the first barrel, and at least one second guide groove including an end separated from the first guide groove and another end connected to the first guide groove to guide the elastic moving pin so that the elastic moving pin returns into the first guide groove when the elastic moving pin is separated from the first guide groove. The second barrel rotates in an optical axis direction and supports the first barrel so that the first barrel moves relative to the optical axis direction.