Provided is a thin slide unit which allows, in a case where two ball plates each formed with a track-like ball groove are combined to thereby construct an endless circulation path for balls, by merely directly connecting the two ball plates without using a guide plate, balls to smoothly circulate, and a slider to smoothly reciprocate with respect to a guide rail. An endless circulation path for the balls of the slider is formed such that the two ball plates each formed with the track-like ball groove are caused to face each other, and that the ball plates are directly connected. Peripheral sides of the two ball plates oppose to each other, to thereby form a load opening portion for causing the balls in the endless circulation path to contact a rolling groove of the guide rail, and form a scooping-up portion for raising the balls from the rolling groove to guide the balls into the endless circulation path.