An image processing apparatus comprising: a transport unit (22, 73) configured to transport (27, 28; 71, 72) a sheet; an access unit (51, 52) having an access range and configured to access a storage medium attached to the sheet transported by the transport unit wherein the time during which a sheet attached with a storage medium transported by the transport unit passes the access range of the access unit (51, 52) is hereindefined as the passing time; a first determination unit (30, 321) configured to determine a length of an access time required for the access unit (51, 52) to complete access of a respective amount of data from a time when the access is started; a change unit configured to control the transport unit such that, when the first determination unit (30, 321) determines that the access time is a first length, the passing time is larger as compared with the passing time when the first determination unit (30, 321) determines that the access time is a second length shorter than the first length; a correction storage unit (322, 341) configured to store the relationship between respective amounts of data and numbers of corrections and the relationship between respective numbers of corrections and correction information wherein the change unit is configured to control the transport unit using the correction information; and an update unit configured to, when an access of the respective amount of data to the storage medium is not normally completed, update the stored number of corrections corresponding to the respective amount of data such that the passing time for a subsequent sheet with the same amount of data is increased. a transport unit (22, 73) configured to transport (27, 28; 71, 72) a sheet; an access unit (51, 52) having an access range and configured to access a storage medium attached to the sheet transported by the transport unit wherein the time during which a sheet attached with a storage medium transported by the transport unit passes the access range of the access unit (51, 52) is hereindefined as the passing time; a first determination unit (30, 321) configured to determine a length of an access time required for the access unit (51, 52) to complete access of a respective amount of data from a time when the access is started; a change unit configured to control the transport unit such that, when the first determination unit (30, 321) determines that the access time is a first length, the passing time is larger as compared with the passing time when the first determination unit (30, 321) determines that the access time is a second length shorter than the first length; a correction storage unit (322, 341) configured to store the relationship between respective amounts of data and numbers of corrections and the relationship between respective numbers of corrections and correction information wherein the change unit is configured to control the transport unit using the correction information; and an update unit configured to, when an access of the respective amount of data to the storage medium is not normally completed, update the stored number of corrections corresponding to the respective amount of data such that the passing time for a subsequent sheet with the same amount of data is increased.