1. An information processing device comprising: a coder for coding an inputted information signal; a rate controller for controlling a coding rate of the coder in accordance with complexity of the information signal and controlling a coding amount per unit time in the coding process so that an average value of the coding amount can be approximate to an average rate which is previously set; a temporary memory unit for temporarily memorizing the coded data; and an information processing unit for processing the data memorized in the temporary memory unit, wherein the information processing unit measures an information processing rate in the information processing, and the rate controller adjusts the average rate so that the average rate is below the information processing rate measured by the information processing unit.