To provide a stamp capable of affixing a seal such as date and time (hour/minute) or date/time and location (latitude, longitude, altitude, etc.) onto a regular paper or the like at any time and anywhere.

A method for affixing the seal comprises (1) utilizing a standard wave for electric wave clocks or GPS satellite electric wave; (2) providing a stamp I with an electric wave receiving antenna 2, an electric wave receiving IC3, one-chip microcomputer 4, an ink-jet fixed head 5, a power supply 7 and a side switch for sealing 8; (3) calculating the date/time or date/time/location by the microcomputer 4 based on an electric wave receiving information; and (4) controlling the microcomputer 4 so as to inject ink particles instantly from the nozzle corresponding to the seal pattern among the nozzles with a series and mesh-like arrangement constituting the above fixed head 5 onto the sealing surface by pressurizing action.