To provide a construction site crime prevention system capable of effectively preventing invasion of a suspicious person illegally invading a building through a temporary scaffold and the like installed in a construction site of the building, an apartment, and the like and reducing burden of monitoring work.

This construction site crime prevention system is provided with a portable transmitter 1 carried by a site worker for transmitting a worker identification signal, an invasion detection sensor 2 arranged in a place vulnerable to invasion into the building, a terminal apparatus 3 checking presence/absence of receipt of the worker identification signal from the portable transmitter 1 in response to a detection output from the invasion detection sensor 2 and determining the suspicious person if no identification signal is received to transmit an alarm signal, and a management apparatus 4 installed in a construction management office for operating an alarm 4d in response to the alarm signal received from the terminal apparatus 3.