IMAGE FORMING DEVICE ACQUIRING EVALUATION VALUE FOR EVALUATING REUSABILITY OF CARTRIDGE

A controller of an image forming device is configured to perform: an elapsed time acquisition process; an evaluation value acquisition process; and an outputting process. The elapsed time acquisition process acquires a length of elapsed time in each of a first time period and a second time period. The evaluation value acquisition process acquires a first evaluation value for the first time period and a second evaluation value for the second time period. Each of the first and second evaluation values specifies a degree of change in a quality of colorant in a cartridge during a corresponding one of the first and second time periods and is based on the length of elapsed time acquired in the elapsed time acquisition process and an ambient environment of the cartridge affecting the quality of the colorant. The outputting process outputs an output value reflecting both the first and second evaluation values.