The maintenance management device 3 includes an error status diagnosis unit 11, a grace period estimation unit 14, a maintenance cost estimation unit 15, and a screen display unit 17. When the error status diagnosis unit 11 has diagnosed the occurrence of an anomaly, the grace period estimation unit 14 estimates a first grace period leading up to the occurrence of a failure. The maintenance cost estimation unit 15 estimates the cost of corrective maintenance incurred when the failure occurs after the elapse of the first grace period. The screen display unit 17 displays a combination of the first grace period and the cost of corrective maintenance. Alternatively, the grace period estimation unit 14 estimates a second grace period over which preventive maintenance may be postponed without a failure.