PURPOSE: To efficiently and easily recognize the character which is rich in variety in its writing order of a stroke and of large deformation by extracting the feature of character shape by a simple curved line constituent element to constitute the stroke and its connection.

CONSTITUTION: An on-line character input device 11 reads a handwritten character, and gives time sequentially stroke information to a curved line construction analyzing part 12. The curved line construction analyzing part 12 inputs the stroke information, and analyzes curved line construction, and extracts the feature in which the overall construction of a character shape not based on the order in which the stroke is written is described. Then, a matching part 13 matches the feature of the input character shape obtained by the curved line construction analyzing part 12 and the standard model of a character shape model part 14 with each other, and recognizes an inputted diagram. Namely, the overall construction of the character shape is described without being influenced by local deformation. Thus, the variety of the deformation of the character can be dealt with, and further, construction description for the on-line input character not based on the order in which the stroke was written can be obtained.