PURPOSE: To provide a parking lot management system which manages a parking lot where a guard device restricting entrance is installed for respective garages for rent by the month and by the hour.

CONSTITUTION: An entrance/exit management device 10 installed near the gateway of the parking lot, a garage management device 30 controlling the driving of the guard device and a central management device 20 managing the whole parking lot based on the output of the entrance/exit management device 10 and the output of the garage management device 30 are provided. Thus, the parking lot is managed by the month and by the hour by an identification code for hourly rent, an identification code for monthly rent and a card 40 where the identification code for hourly rent is printed.