A handwriting input/output system that allows letters, characters and figures to be input by hand. The handwriting input/output system includes an imaging device that captures and transmits the image of a medium provided with a writing area having a dot pattern that defines coordinate information and code information, a dot pattern analysis device that calculates trajectory information by storing the image data of the dot pattern and analyzing the code of the image data, a trajectory recognition device recognizes the trajectory information of the letter, character, and figure traced on the writing area based on a change in the analyzed coordinate information, and a process instruction device transmits a process instruction based on the recognized information together with the trajectory information to an information processing device, whereby a letter, character, or figure can be input by hand.