A handwriting input apparatus configured to display stroke data handwritten based on a position of an input unit contacting a touch panel, the handwriting input apparatus comprising: circuitry configured to implement: a handwriting recognition control unit configured to recognise stroke data received through the touch panel and to convert the stroke data into text data, and an authentication control unit configured to authenticate a user when the received stroke data conforms to previously registered handwriting signature data, said handwriting signature data comprising stroke data used for signing in; the handwriting input apparatus characterized in that it further comprises: a display unit configured to display, in response to the authentication control unit determining that a user has been successfully authenticated, an operation guide including one or more selectable candidates, the selectable candidates comprising an operation command configured to sign in by handwriting and a character string candidate, the operation command displaying text data corresponding to a signature to be used for signing in; and a candidate display timer control unit configured to generate a timing for starting display of the one or more selectable candidates and a timing for stopping display of the one or more selectable candidates, wherein the operation guide is not displayed when further stroke data is received through the touch panel before a predetermined time has elapsed. a handwriting recognition control unit configured to recognise stroke data received through the touch panel and to convert the stroke data into text data, and an authentication control unit configured to authenticate a user when the received stroke data conforms to previously registered handwriting signature data, said handwriting signature data comprising stroke data used for signing in; the handwriting input apparatus characterized in that it further comprises: a display unit configured to display, in response to the authentication control unit determining that a user has been successfully authenticated, an operation guide including one or more selectable candidates, the selectable candidates comprising an operation command configured to sign in by handwriting and a character string candidate, the operation command displaying text data corresponding to a signature to be used for signing in; and a candidate display timer control unit configured to generate a timing for starting display of the one or more selectable candidates and a timing for stopping display of the one or more selectable candidates, wherein the operation guide is not displayed when further stroke data is received through the touch panel before a predetermined time has elapsed. a display unit configured to display, in response to the authentication control unit determining that a user has been successfully authenticated, an operation guide including one or more selectable candidates, the selectable candidates comprising an operation command configured to sign in by handwriting and a character string candidate, the operation command displaying text data corresponding to a signature to be used for signing in; and a candidate display timer control unit configured to generate a timing for starting display of the one or more selectable candidates and a timing for stopping display of the one or more selectable candidates, wherein the operation guide is not displayed when further stroke data is received through the touch panel before a predetermined time has elapsed.