A lamp socket for receiving a LED lamp including a light tube shaped into a straight tube and a base provided to an end of the light tube, wherein the base is provided with a L-shaped pin including a contact piece extending along an axial direction of the light tube and an extension piece extending along a radial direction of the light tube from a tip of the contact piece, at its end surface in the axial direction of the light tube, and the lamp socket comprises: a socket body that includes a body and a cover, that is formed into a hollow box shape and that is provided with an insertion hole at a primary surface of the cover; a conductive plate for power supply, the conductive plate being formed into a band plate shape along a lengthwise direction of said conductive plate, and the conductive plate being positioned inside the socket body so as to have a width direction parallel to a direction extending along the axial direction of the light tube and to face the insertion hole, and the conductive plate has a first surface opposite to a central axis of the insertion hole, and a first space is provided between a second surface of the conductive plate and an inner periphery of the socket body, and a second space is provided between a bottom surface of the body facing the primary surface and the conductive plate, and a third space is provided between the first space and the bottom surface of the body and communicates with the second space so as to form a rotation space together with the second space, wherein the lamp socket is configured such that when the pin of the lamp is inserted into the insertion hole and the lamp is rotated about its axis, the contact piece comes in contact with the first surface of the conductive plate and a rotation track of the extension piece passes through the rotation space, wherein the bottom surface of the body is provided with a first pedestal, the first pedestal has a first mounting face, a second pedestal protrudes from the bottom surface, the second pedestal has a second mounting surface, and the conductive plate is mounted on the first and second mounting surfaces (42a and 41a). a socket body that includes a body and a cover, that is formed into a hollow box shape and that is provided with an insertion hole at a primary surface of the cover; a conductive plate for power supply, the conductive plate being formed into a band plate shape along a lengthwise direction of said conductive plate, and the conductive plate being positioned inside the socket body so as to have a width direction parallel to a direction extending along the axial direction of the light tube and to face the insertion hole, and the conductive plate has a first surface opposite to a central axis of the insertion hole, and a first space is provided between a second surface of the conductive plate and an inner periphery of the socket body, and a second space is provided between a bottom surface of the body facing the primary surface and the conductive plate, and a third space is provided between the first space and the bottom surface of the body and communicates with the second space so as to form a rotation space together with the second space, wherein the lamp socket is configured such that when the pin of the lamp is inserted into the insertion hole and the lamp is rotated about its axis, the contact piece comes in contact with the first surface of the conductive plate and a rotation track of the extension piece passes through the rotation space, wherein the bottom surface of the body is provided with a first pedestal, the first pedestal has a first mounting face, a second pedestal protrudes from the bottom surface, the second pedestal has a second mounting surface, and the conductive plate is mounted on the first and second mounting surfaces (42a and 41a).