A headlamp for vehicle, comprising a plurality of light function modules (20, 30, 40), wherein at least one of the plurality of light function modules comprises: a light source module having a light source; a dissipation module disposed behind the light source module and configured to dissipate heat generated by the light source, the dissipation module being optionally common to several of the light function modules,; and a light distribution module disposed in front of the light source module and configured to distribute light emitted by the light source module, and wherein the light distribution module comprises: a focusing lens configured to concentrate incident light; a collimator lens configured to emit light, incident from the light source module, in form of parallel light; a shield retainer assembly configured to shield at least part of light emitted by the focusing lens and reflect the at least part of light emitted by the focusing lens; a light distribution case configured to accommodate the focusing lens, the collimator lens and the shield retainer assembly; and a light distribution cover configured to cover the light distribution case, wherein the light distribution case comprises: a light distribution head part having a collimator lens accommodating space and a collimator lens insertion hole formed at a rear of the light distribution head part; and a light distribution tail part connected to a front of the light distribution head part, wherein the light distribution module further comprises a collimator lens retainer which fixes the collimator lens to the light distribution head part, and wherein the collimator lens retainer is coupled to a rear surface of the light distribution head part, wherein the light distribution module further comprises a diffuser which faces a rear surface of the collimator lens, and wherein the diffuser is disposed behind the collimator lens retainer. a light source module having a light source; a dissipation module disposed behind the light source module and configured to dissipate heat generated by the light source, the dissipation module being optionally common to several of the light function modules,; and a light distribution module disposed in front of the light source module and configured to distribute light emitted by the light source module, and a focusing lens configured to concentrate incident light; a collimator lens configured to emit light, incident from the light source module, in form of parallel light; a shield retainer assembly configured to shield at least part of light emitted by the focusing lens and reflect the at least part of light emitted by the focusing lens; a collimator lens configured to emit light, incident from the light source module, in form of parallel light; a shield retainer assembly configured to shield at least part of light emitted by the focusing lens and reflect the at least part of light emitted by the focusing lens; a light distribution case configured to accommodate the focusing lens, the collimator lens and the shield retainer assembly; and a light distribution cover configured to cover the light distribution case, a light distribution head part having a collimator lens accommodating space and a collimator lens insertion hole formed at a rear of the light distribution head part; and a light distribution tail part connected to a front of the light distribution head part, wherein the light distribution module further comprises a collimator lens retainer which fixes the collimator lens to the light distribution head part, and wherein the collimator lens retainer is coupled to a rear surface of the light distribution head part, wherein the light distribution module further comprises a diffuser which faces a rear surface of the collimator lens, and wherein the diffuser is disposed behind the collimator lens retainer. wherein the light distribution module further comprises a collimator lens retainer which fixes the collimator lens to the light distribution head part, and wherein the collimator lens retainer is coupled to a rear surface of the light distribution head part, wherein the light distribution module further comprises a diffuser which faces a rear surface of the collimator lens, and wherein the diffuser is disposed behind the collimator lens retainer.