To dispense with a sensor for detecting the residual amt. of ink by calculating the residual amt. of ink by using a count means counting the number of jet commands of ink.

A second control circuit 34 converts the jet data based on the dot data received from a first control circuit 33 to serial data by a parallel/ serial converter 38 and the serial data and a printing timing signal are outputted to a drive circuit 40. The drive circuit 40 converts the serial data to parallel data by a serial/parallel converter 42 and drives a printing head 10 through a driver 43 to inject ink to perform printing. A dot counter 39 counts the number of jet commands in parallel to printing operation to count the consumption amt. of ink. Since the dot counter 39 outputs the data corresponding to the number of jet dots, a CPU 36 can calculate the residual amt. of ink on the basis of this output and the number of injectable dots determined from the preliminarily cleared total amt. of ink of a new cartridge.