A shelf for a showcase in which a roller unit is formed with holding grooves on both sides of a bottom surface of a U-shaped roller plate. Fixing frames coupled with the roller plate include a bottom part, formed with a vertical rib to be fitted into the holding groove of the roller plate, and a vertical wall surrounding an outside of the roller plate and formed with a horizontal rib closing opened parts of fitting grooves of the roller plate, so that the fixing frames are mounted on both sides of the roller plate of the roller unit in pair correspondingly to each other. The vertical walls are formed with screw-coupling holes at front and rear ends in accordance with screw holes punched at both side walls of the end caps so as to be integrally coupled together by coupling screws.