For a temperature adjustment process that uses high viscosity ink and is based on a first table, in a low temperature environment, an ink refill failure may occur and lower density may appear in high duty printing. Also for a temperature adjustment process that uses high viscosity ink and is based on second and third tables, in a low temperature environment, an ink refill failure may occur and lower density may appear. On the other hand, for a temperature adjustment process that employs a fourth table, a smaller pre-heat pulse width than that for the first table, for the conventional temperature adjustment, is employed in the same low temperature environment. Therefore, an ink refill failure does not occur, and horizontal or vertical gaps do not appear during high duty printing.