Security is gaining awareness and importance in recent years. And the access control system is a vital link in the security chain. There are many security systems available in the market today, but the document offered here is a cost-effective electronic system. Low operating energy consumption, flexible and user-friendly mechanical designs are the merits of this project. The paper presents the authorized access system technology using the 89c51 microcontroller and it has the added benefit of having more than one password to enter the building. Security includes several areas such as personal security, organizational security and among others. Security access control is an important aspect of any system. This is to ensure that an authenticated user only accesses what they are authorized to do and no more. Almost every application dealing with finance, privacy, or defense includes some form of access control. Access control involves determining the authorized activities of legitimate uses that occur in each attempt by a user to access a resource in the system. These days, locks and keys are not enough to maintain a secure environment against unwanted or uncontrolled visitors. To gain access to mechanical security systems, such purely mechanical systems are widely used and can be easily defrauded. This article presents an access control system that uses keypad technology. These design features are able to: • Give the installation a multiple access system with one administrator and 5 users. (user number can be extended depending on the size of EEPROM used).• User can access only the system• Viewed all the features provided using LCDCIRCUIT DIAGRAMTh...... middle paper......economic room access system using a microcontroller. It is an inexpensive, low power consumption, compact size and self-contained system. The microcontroller compares the passwords entered by the keyboard. If these passwords are correct, the microcontroller provides the necessary control signals to open the door, otherwise the door remains closed. The alarm will come on whenever the door is forced open.REFERENCES:1. Inderpreet Kaur, “Microcontroller based home automation system with security”, IJACSA, vol 1, no 6, December 20102. Sadedue reza khan, “Development of low cost private office access control system (OACS) », IJESA, vol 2, no.2, June 20123. “Home automation costs” totalavcontrol.co.uk.retrived 2010-0 2-184. LCD module 16*2 January 21, 2012, (online) available: http//www.LCD module .de/eng/pdf/doma/dip204-4e.pdf5. Bart Huyskens", an introduction to microcontroller programming”