A lamp, lamp holder, and a power supply substrate that allow easy fabrication of a backlight assembly or a power supply module for a display device are presented. The lamp includes a lamp tube and an electrode that extends outside the lamp tube to form a lamp lead. The lamp holder includes a body for holding the lamp tube and a power supply member for providing voltage to the lamp lead. A power supply module includes a power supply substrate combined with a lamp holder holding the lamp. The lamp holders are fixed to fixing portions of the power supply substrate or to fixing holes of a connection plate. As the design allows easy separation of the lamp holders from the power supply substrate, building a backlight assembly or a display device is facilitated.