A lamp holder includes a mounting portion, a lamp holding part which is connected to the mounting portion, and includes an end capable of surrounding a peripheral surface of a lamp, and is capable of being elastically opened and deformed during attaching and detaching of the lamp. The lamp holder also includes a recessed portion positioned at a surface of the lamp holding part that is opposite to the lamp and located at a position between an end portion and a connecting region of a mounting portion, such that the recessed portion allows the lamp holding part to bend so that the end portion is displaced in a direction away from the peripheral surface of the lamp.