In the present invention, provided is a monitoring device (10) including an operating-state-change information acquisition unit (11) that acquires operating-state-change information indicating a time-series change in operating states of an electrical device, the device being capable of assuming multiple types of operating states, a standard transition pattern storage unit (12) that stores standard transition pattern information indicating a pattern of transition between operating states generated in a normal electrical device, and a monitoring unit (13) that determines whether or not the electrical device is normal using the operating-state-change information and the standard transition pattern information.