The invention discloses a blackboard. The key point of the technical scheme is as follows: the blackboard comprises a blackboard body and erasing parts. A curtain device is arranged on the blackboardbody and comprises a first sliding bar, a second sliding bar and a curtain body. The curtain body is placed in the first sliding bar in a shrinking manner, a resetting part is arranged in the first sliding bar, a fixing part is arranged on the second sliding bar, the first sliding bar and the second sliding bar stretch along the longitudinal direction of the blackboard and are matched with the length dimension of the blackboard body in the longitudinal direction, a limiting part is arranged in the blackboard body, the erasing parts are arranged at two ends of the transverse direction of the blackboard body, each erasing part comprises erasing board and a driving mechanism, a control switch is arranged on the blackboard body, and reversing switches are arranged on the first sliding bar andthe second sliding bar. The blackboard can erase and retain an appointed region automatically, so that the curtain is accommodated freely and can be movably fixed to any position of the blackboard.