To provide a medical data storage device that requires high speed and reliability and is resistant to failure caused by external factors such as a disaster.

A medical data storage device includes a network control part for transmitting and receiving medial data between a server and modalities connected to a in-house network, a storage part comprising a cache memory and multiple nonvolatile memories for temporarily storing the medical data, a disaster detection part for detecting a disaster or a failure, a disaster level determination part for determining a disaster level from a signal of a disaster or a failure detected by the disaster detection part, a storage control part for performing degeneracy operation of the storage part according to the disaster level, and a remote replication part for replicating with a remote place the medical data received after the start of the degeneracy operation according to available circuit volume, following the information of priority given to the medical data, when at least one of multiple communication lines is available.