The verification system of this invention comprises an image forming apparatus 1 having verification function and a card reader 2 for reading a user ID from a card. The image forming apparatus 1 is capable of performing short-range radio communication with a portable instrument 3. The portable instrument 3 receives a polling command transmitted by the image forming apparatus 1 and sends back its own identification code if it is located near the image forming apparatus 1. The image forming apparatus 1 permits usage of all the functions thereof if it verifies that user is an officially permitted person according to user ID read by the card reader 2 and the identification code sent back from the portable instrument 3. Consequently, there is provided a verification system having a high security level and convenient for use or a verification system which permits usage of its apparatus and other related devices within an appropriate range depending on the security level of a verified method.