To provide an inexpensive and secure method for authenticating settlement information, without installing encryption and decryption devices.

In an authenticating settlement information method, a cellular phone (6) sends and receives information about settlement to and from an adjusting machine (5) and communicates with a management device (7) via a wireless line. The adjusting machine (5) receives a piece of settlement information sent from the management device (7) via the cellular phone (6) and receives another piece of settlement information sent from the management device (7) via a communication network 90 without the intervention of the cellular phone (6). The adjusting machine (5) has a comparison part (51) for comparing the two pieces of settlement information. The pieces of settlement information are verified and settlement is carried out when the settlement information is determined to be true.