A memory refreshing apparatus configured to refresh a memory at a refresh cycle, the memory refreshing apparatus comprises: a normal patrol controlling section configured to control a normal patrol operation that reads all addresses in the memory to scan the addresses for detection of data errors; and characterized in that the memory refreshing apparatus further comprises: an additional patrol controlling section configured to control an additional patrol operation that, if a first error in the memory is detected during the normal patrol operation performed by the normal patrol controlling section, reads data at an address of an error occurring area in which the first error has occurred for detection of errors, a monitoring interval of the additional patrol operation being shorter than an interval performed by the normal patrol controlling section; a measuring section configured to measure, if a second error is detected in the error occurring area during the additional patrol operation performed by the additional patrol controlling section, an error frequency representing information of error in the error occurring area; and a refresh cycle adjusting section configured to adjust the refresh cycle in accordance with the error frequency measured by the measuring section; wherein either the measuring section measures, as the error frequency, the number of errors in the error occurring area per predetermined time period, or if a plurality of the error occurring areas are detected during the additional patrol operation performed by the additional patrol controlling section, the measuring section measures, instead of the error frequency, the number of the error occurring areas. a normal patrol controlling section configured to control a normal patrol operation that reads all addresses in the memory to scan the addresses for detection of data errors; and characterized in that the memory refreshing apparatus further comprises: an additional patrol controlling section configured to control an additional patrol operation that, if a first error in the memory is detected during the normal patrol operation performed by the normal patrol controlling section, reads data at an address of an error occurring area in which the first error has occurred for detection of errors, a monitoring interval of the additional patrol operation being shorter than an interval performed by the normal patrol controlling section; a measuring section configured to measure, if a second error is detected in the error occurring area during the additional patrol operation performed by the additional patrol controlling section, an error frequency representing information of error in the error occurring area; and a refresh cycle adjusting section configured to adjust the refresh cycle in accordance with the error frequency measured by the measuring section; wherein either the measuring section measures, as the error frequency, the number of errors in the error occurring area per predetermined time period, or if a plurality of the error occurring areas are detected during the additional patrol operation performed by the additional patrol controlling section, the measuring section measures, instead of the error frequency, the number of the error occurring areas. an additional patrol controlling section configured to control an additional patrol operation that, if a first error in the memory is detected during the normal patrol operation performed by the normal patrol controlling section, reads data at an address of an error occurring area in which the first error has occurred for detection of errors, a monitoring interval of the additional patrol operation being shorter than an interval performed by the normal patrol controlling section; a measuring section configured to measure, if a second error is detected in the error occurring area during the additional patrol operation performed by the additional patrol controlling section, an error frequency representing information of error in the error occurring area; and a refresh cycle adjusting section configured to adjust the refresh cycle in accordance with the error frequency measured by the measuring section; wherein either the measuring section measures, as the error frequency, the number of errors in the error occurring area per predetermined time period, or if a plurality of the error occurring areas are detected during the additional patrol operation performed by the additional patrol controlling section, the measuring section measures, instead of the error frequency, the number of the error occurring areas.