There is provided a session management method for a computer system including an initiator, and a storage system coupled to the initiator via a network. The initiator includes an interface coupled to the network, a processor and a memory. The storage system includes an interface coupled to the network, a memory and a processor. The session management method comprising the steps of: executing, by the initiator, health check for diagnosing a status of a session established between the initiator and the storage system in the case of which no data is input/output to/from the storage device for a first predetermined period; and cutting off and re-establishing, by the initiator, the session with the storage system at a timing of executing the health check in the case of which no data is input/output to/from the storage system for a second predetermined period.