A tube cutter includes a main device, a blade and a controller. The main device includes a fixed member and a movable member, wherein the movable member is movably connected to the fixed member, and a cutting space is formed between the fixed member and the movable member. The blade is fixed to the main device, and the blade has a blade portion in the cutting space. The controller, which is provided on the main device, can be operated to move the movable member for changing a size of the cutting space.