A cutter unit is attached to a carriage in a predetermined direction, the carriage moving in a cutting direction of a sheet. A first set of first fitting sections and a second set of second fitting sections are provided as groups of fitting sections provided at positions, which face each other, on the carriage and the cutter unit. The first fitting sections and the second fitting sections each of which are fitted to each other in a predetermined direction. When the cutter unit is attached to the carriage, the fitting of the first fitting sections starts before the fitting of the second fitting sections.