A lamp for a vehicle, comprising: a mirror housing into which a mirror is installed; and a signal lamp disposed on one surface of the mirror housing, wherein the signal lamp includes a reflection unit, a lens unit disposed a predetermined distance apart from the reflection unit and having a half mirror installed on at least one surface of the lens unit, and a first light source unit, wherein the first light source unit includes: a light guide disposed between the reflection unit and the lens unit and is about the same distance apart from the reflection unit and the lens unit; and one or more light sources (222a, 222b) disposed on at least one side of the light guide, wherein the light guide facing the reflection unit and the half mirror includes a pair of parallel sides that face the reflection unit and the half mirror, wherein the signal lamp is configured to repeatedly form a plurality of images with a predetermined ratio of similarity with respect to the shape of the first light source unit via the half mirror, wherein the reflection unit is configured to reflect light at a predetermined angle for the light to travel back toward the half mirror in response to light generated by the first light source unit being reflected from the half mirror, and wherein surfaces of the reflection unit and the half mirror that face each other are either substantially flat surfaces extending in parallel with each other or curved surfaces having about the same curvature, and wherein the signal lamp further includes a support unit disposed between the reflection unit and the lens unit and having an opening of a predetermined size, wherein the light guide is disposed on a side of an outer circumferential end of the opening of the support unit. a mirror housing into which a mirror is installed; and a signal lamp disposed on one surface of the mirror housing, wherein the signal lamp includes a reflection unit, a lens unit disposed a predetermined distance apart from the reflection unit and having a half mirror installed on at least one surface of the lens unit, and a first light source unit, wherein the first light source unit includes: a light guide disposed between the reflection unit and the lens unit and is about the same distance apart from the reflection unit and the lens unit; and one or more light sources (222a, 222b) disposed on at least one side of the light guide, wherein the light guide facing the reflection unit and the half mirror includes a pair of parallel sides that face the reflection unit and the half mirror, wherein the signal lamp is configured to repeatedly form a plurality of images with a predetermined ratio of similarity with respect to the shape of the first light source unit via the half mirror, wherein the reflection unit is configured to reflect light at a predetermined angle for the light to travel back toward the half mirror in response to light generated by the first light source unit being reflected from the half mirror, and wherein surfaces of the reflection unit and the half mirror that face each other are either substantially flat surfaces extending in parallel with each other or curved surfaces having about the same curvature, and wherein the signal lamp further includes a support unit disposed between the reflection unit and the lens unit and having an opening of a predetermined size, wherein the light guide is disposed on a side of an outer circumferential end of the opening of the support unit. a light guide disposed between the reflection unit and the lens unit and is about the same distance apart from the reflection unit and the lens unit; and one or more light sources (222a, 222b) disposed on at least one side of the light guide, wherein the light guide facing the reflection unit and the half mirror includes a pair of parallel sides that face the reflection unit and the half mirror, wherein the signal lamp is configured to repeatedly form a plurality of images with a predetermined ratio of similarity with respect to the shape of the first light source unit via the half mirror, wherein the reflection unit is configured to reflect light at a predetermined angle for the light to travel back toward the half mirror in response to light generated by the first light source unit being reflected from the half mirror, and wherein surfaces of the reflection unit and the half mirror that face each other are either substantially flat surfaces extending in parallel with each other or curved surfaces having about the same curvature, and wherein the signal lamp further includes a support unit disposed between the reflection unit and the lens unit and having an opening of a predetermined size, wherein the light guide is disposed on a side of an outer circumferential end of the opening of the support unit.