A dot-matrix printer can register dot character patterns input through an external unit (11). It has a circuit (17) for correcting a dot character pattern. This circuit (17) checks a dot character pattern stored in a buffer memory (13) to determined whether any two adjacent dots of the pattern which are arranged in the printing direction contact or not. If the dots contact, one of them is erased, thus correcting the dot character pattern. The corrected dot character pattern is stored in a character generator (18). The corrected pattern is supplied from the character generator (18) to a drive circuit (20). The drive circuit (20) drives a print head, etc., whereby the dot character corresponding to the pattern read from the character generator is printed.