A light bulb socket adapter includes an adapter base and at least one lamp holder. The adapter base includes a base having a ring contact and a tip contact. The at least one lamp holder is oscillatingly mounted to the adapter base through an oscillating connection assembly. The oscillating connection assembly has a ball-holding mechanism mounted on an end opposite to the base of the adapter base, and at least one ball fixedly connected with the respective lamp holder and oscillatingly engaged with the ball-holding mechanism. The present invention allows the light bulb mounted thereon to irradiate in a desired direction and a bayonet-type bulb to be mounted in a conventional screw-type socket without requiring an additional socket adapter.