To solve the cumbersome problem that low-limit overload detection sensitivity corresponding to the size of an individual shutter apparatus has to be input as an initial value into the individual shutter apparatus.

An initial setting mode is provided before a normal operation of a shutter apparatus; a shutter full-closing operation is performed by low low-limit overload detection sensitivity set without reference to the size of the shutter apparatus in the initial setting mode; and the low-limit overload detection sensitivity for use in the subsequent normal operation is determined, so that the low-limit overload detection sensitivity can be input into the apparatus in such a manner as to correspond to the size of the individual shutter apparatus.