1. A job executing system in which, with respect to a same processing object, designated jobs are executed in a time series, comprising: job management means for managing an input-related candidate job which executes chiefly input processing, and an output-related candidate job which executes chiefly output processing; and job synthesizing means for generating, according to a user's operation, a synthetic job constituted by an input-related candidate job which has been already executed, and an output-related candidate job which will be executed hereafter.