To provide a monitoring device, a monitoring method, and a monitoring system such that a monitoring camera can be easily operated.

The monitoring device includes a first recording section 21 which stores video data acquired through a network 2 from monitoring cameras 1a to 1n generating video data based upon videos of monitored places, a decoding section 14 which decodes the video data read out of the first recording section 21, an output section 15 which outputs the video data decoded by the decoding section 14 to a display device 6 displaying videos, and a control section 12 which superposes a control picture for controlling the monitoring cameras 1a to 1n on the videos displayed on the display device 6 and controls the monitoring cameras 1a to 1n according to control instructions received from a controller 4 to control the monitoring cameras 1a to 1n.