A digital transmission apparatus and a method thereof and a digital reception apparatus are provided. A frame body processor converts incoming data and outputs a frame body, a system information generator generates system information, which is necessary for processing the data at a reception apparatus, by using a different processing method from the frame body processing method of the frame body processor, a frame generator multiplexes data of the frame body, a header of the frame, and the system information, thereby generating a frame, and a signal processor up-coverts a signal of the frame and transmits the signal to the reception apparatus.