A novel cleaning device for the inner wall of an injection mold comprises a cleaning frame, a cleaning box fixedly arranged at the upper end of the cleaning frame and a cleaning machine. The cleaningbox is internally provided with a containing cavity. The front inner wall and the rear inner wall of the containing cavity are internally provided with moving guide grooves which extend up and down. The front and the back of the cleaning machine are symmetrically provided with sliding arms which coordinate with the moving guide grooves. The sliding arms are provided with beveling grooves. The lower end of the cleaning machine is provided with a cleaning rod in an operative manner. An outer circle of the cleaning rod is provided with a cleaning brush which is used for cleaning the inner wall ofthe mold. The left and the right of the cleaning machine are symmetrically provided with pressing grooves with downward openings. The pressing grooves are internally provided with pressing arms in anup-down sliding manner. The upper ends of the pressing arms are fixedly provided with compressed springs, and the upper ends of the compressed springs are fixedly connected with the top walls of thepressing grooves.