PURPOSE: To prevent the power supply to unnecessary elements and to prevent the degradation of elements due to side reaction, by providing a monitor circuit which selects electrochromic elements and confirms and stores their operation completion.

CONSTITUTION: At the start time, not only a monitor flip-flop circuit F is cleared but also a switch SW1 is turned on by the pulse of a gate G2, and a high potential VD is inputted to a comparing circuit COMP, and all outputs are made H-level, and electrochromic elements S1WSn develop colors by the output of a comparator COMPA, thus setting the stop close state. Circuits F1WFn are set by the completion of coloring. A switch SW2 is turned on by the end of pulses of the gate G2, and a potential SIGL (for auto) is inputted to the comparing circuit COMP; and when outputs of comparators COMP1WCOMPi become L- level, elements S1WSi extinguish colors by the output of a comparator COMPB, and circuits F1WFi are reset by the completion of color extinction.