An LED light bulb includes a power conversion board, at least one light source baseboard electrically connected to the power conversion board, a heat sink and a light transparent shell to hold the light source baseboard. The heat sink has a wedged groove with a first holding portion formed thereon. The light transparent shell includes a sphere and a neck wedged in the wedged groove. The sphere and neck have an inner wall surrounded to hold the power conversion board and an outer wall opposite to the inner wall. The neck has a longitudinal shell retaining portion on the outer wall corresponding and fastening to the first holding portion and at least one transverse shell retaining portion. The wedged groove has at least one second holding portion corresponding and fastening to the transverse shell retaining portion to restrict relative turning of the light transparent shell and heat sink.