Abstract: A computer managing system includes an active system computer having a heart beat transmission processing unit for transmitting a heart beat signal indicating that an active system computer is being operated in normal to a spare system computer, and transmitting the heart beat signal to a first control unit; a spare system computer including a monitor request processing unit for transmitting a monitoring request of the active system computer to the first control unit in accordance with a determination result of whether or not a fault has occurred in the active system computer; and the first control unit including a heart beat transmit instruction processing unit for instructing a transmission of the heart beat signal to the first control unit, to the active system computer, when receiving the monitoring request from the spare system computer.