Abstract: A dot-matrix printer can register dot character patterns input through an external unit. The present invention has a circuit for checking and correcting a dot character pattern. This circuit checks a dot character pattern stored in a buffer memory to determine whether any two adjacent dots of the pattern, which are arranged in the printing direction, are in 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. The corrected pattern is supplied from the character generator to a drive circuit. The drive circuit drives a print head, etc., whereby the dot character corresponding to the pattern read from the character generator is printed.