A data processing apparatus includes one or a plurality of input portions, one or a plurality of output portions, a plurality of compressing/expanding devices which compress data-to-be-outputted included in a job inputted from any one of an input portions and expand the compressed data-to-be-outputted, and a job discrimination portion which discriminates whether the job inputted from any one of the input portions is not required to be outputted without delay. Depending on a discrimination result of the job discrimination portion, a controller controls operation assignment of a plurality of compressing/expanding devices and activates assigned compressing/expanding devices for the job.