PURPOSE: To heighten processing efficiency with a simple process by finding a distributed value by estimating the recorded pitch of each character for a segmented character line, and discriminating whether a recorded character is an equal pitch character string or a variable pitch character string with the distributed value.

CONSTITUTION: By inputting a character picture signal from a photoelectric converting part 1 to a line detecting and segmenting part 2, a character line is segmented, and a projection pattern in a vertical directions to its line direction is generated at a projection generating part 3. A character block generating part 4 divides the character block in order at a position where an inter-character distance having a value larger than a prescribed value is generated. A character posting pitch estimating part 5 estimates the posting pitch of each character for the segmented character line segmented at the line detecting and segmenting part 2, and finds the distributed value of the posting pitch at a distribution arithmetic part 6. A discriminating part 7 discriminates whether a recorded character is the equal pitch character string or the variable pitch character string.