A monitoring method includes acquiring tag identification information
unique to a radio frequency identification tag carried by a person, and
reader identification information about a tag reader that detects the
radio frequency identification tag. Next, attribute information about the
person is acquired based on the tag identification information, and area
information about a detection area of the tag reader is acquired based on
the reader identification information. Finally, it is determined whether
the person carrying the radio frequency identification tag having the
attribute information acquired is allowed to enter into the detection
area based on the area information.