PURPOSE: To shorten the time required for character output by registering characters relating to a character requested to be outputted in a font cache memory associatively in advance.

CONSTITUTION: A character generating means 100 reads the vector font of the character requested to be outputted out of a font ROM 120 and expands it into a dot pattern unless the dot pattern of the character is registered in a font cache memory 110, but when the dot pattern is registered, the dot pattern is read out of the font cache memory 110 and outputted. A relative character associating means 130 associates a character (relative character) which becomes an (n+1)th output requested character with high possibility from an (n)th output requested character. A relative character expanding means 130 expands the vector font of the associative character into a dot pattern and registers it in the font cache 110 unless the dot pattern is registered in the font cache memory 110.