To achieve labor saving of an operator and highly accurate positioning when changing and adjusting a slit cutting position, and achieve space saving of a slitter device, in the slitter device which cuts slits in an object to be cut by a predetermined number of slitter blades.

A shaft 31 is provided with slitter blades 14-1 to 14-5. A movable shaft 42 arranged parallel to the shaft 31 is provided with a movable chuck part 41 equipped with a movable holding arm 51 movable to the slitter blade side, and provided with a single detection sensor 56, 57 moving integrally with the movable chuck part 41. On the basis of detection of a slitter blade to be moved by the detection sensor 56, 57, the slitter blade to be moved is held and moved by the movable holding arm 51.