A printing device controller provided with a first computational processing unit that performs overall control of the device as a whole and a second computational processing unit that consumes less power than the first computational processing unit, the printing device controller including: a RAM (Random Access Memory) having a self-refresh mode; a main control unit whose main processing constituent is the first computational processing unit; and a sub control unit whose main processing constituent is the second computational processing unit. When an instruction to enter a power-saving state is inputted, the main control unit causes the first computational processing unit to store information necessary for returning from the power-saving state into a storage unit and then causes the RAM to enter the self-refresh mode, and the sub control unit then powers off the first computational processing unit.