Indoor positioning technologies to position people with RFID tags and smart phones are progressing rapidly and begin to be put to practical use in o2o services and smart security systems. On the other hand, surveillance systems to position unspecified people are used widely in security and space utilization planning. Some useful systems and services are possible by using the positioning information of people with and without tags, such as a security system for patients in a hospital, an intruder detection system in a building and efficient client services in a large-scale retail store. We consider techniques to detect, track and count people without tags among people with and without them. A device to detect people with and without RFID tags consists of two sub devices. One detects RFID tags within a relatively small area around an antenna and another detects people within the tag detection area. The devices should be installed at any places where people have to walk through to move one area to another in a building.