A lamp for a vehicle includes a cover lens, a housing that is coupled to the cover lens and that defines a lamp space with the cover lens, a light output unit including a plurality of light generation groups that are arranged inside of the lamp space in a first direction, and a light guide that has a three-dimensional (3D) shape and that is configured to guide light from the light output unit in a light output direction. The light guide includes: a first surface that defines a portion of the 3D shape of the light guide and that faces the light output unit, and a second surface that defines a portion of the 3D shape of the light guide and that defines an acute angle with respect to the first surface.