Provided is a lamp for a vehicle capable of forming a beam pattern satisfying the performance requirements by using a micro lens optical system which includes a cylinder lens. The lamp includes a light source portion, a first lens portion which includes a plurality of micro incident lenses, and a second lens portion which includes a plurality of micro exit lenses disposed in front of the plurality of micro incident lenses. Particularly, the lamp forms a beam pattern using a combination of one or more micro incident/exit units. Each of the micro incident/exit units includes one cylinder lens and a plurality of corresponding lenses that correspond to the one cylinder lens, and any one of the micro incident lens or the micro exit lens is the cylinder lens and the other is the corresponding lens.