According to one embodiment, a monitoring system is provided, which has a personal authentication unit and a camera. The personal authentication unit is provided near a security gate and authenticates a person allowed to pass through the security gate. The camera photographs an area near the security gate, in which the personal authentication unit is provided. The monitoring system further has a data generation unit configured to generate personal attribute data about the person authenticated by the personal authentication unit, a person identification unit configured to identify the person authenticated, on the basis of video data generated by the camera, and a monitoring data generation unit configured to generate monitoring data composed of video data and metadata. The video data represents an image including the person identified by the person identification unit. The metadata is associated with the video data and containing the personal attribute data.