An ink-sack-replaceable ink cartridge includes a cartridge body, which includes a bottom wall, two lateral walls extending upward from two sides of the bottom wall, and two end walls extending upward from two ends of the bottom wall and connected to the lateral walls. The bottom wall, the lateral walls, and the end walls jointly define a receiving space. The bottom wall is formed with a through hole. Each of the lateral walls includes a cartridge-body slide coupling section. A cartridge cover includes a top wall and two side walls extending downward from two sides of the top wall. Each of the side walls includes a cartridge-cover slide coupling section. The cartridge-cover slide coupling sections are slidably connectable with the cartridge-body slide coupling sections, so that the cartridge cover is combinable with and separable from the cartridge body through slidable connection for closing or opening the receiving space.