A manufacturer server 110 that determines a first invoice amount or calculates a second invoice amount for an inkjet printer has a billing status acquisition unit 342 that acquires billing status information including actual print volume PV. An actual print volume calculation unit 343 determines (i) if PV is less than or equal to a specific volume V1, in which case the first invoice amount, which is a fixed amount, is determined, and (ii) if PV exceeds V1, in which case the second invoice amount is calculated. An invoice amount calculation unit 344 determines or calculates the first or second invoice amount.