This project is aimed to design a security system for banks using wireless technology GSM. In this project we provide efficient way of security for banks. Which is an advanced door lock system used in the fields where security and secrecy is the primary constraint. Security is a prime concern in our day-today life. Everyone wants to be as much secure as possible. An access control for doors forms a vital link in a security chain. The microcontroller based digital lock access control system that allows only authorized persons to access Doors. It is a low cost so that the concept is implemented by using an 8051 series microcontroller A GSM modem provides the communication interface. It transports device protocols transparently over the network through a serial interface. A GSM modem is a wireless modem that works with a GSM wireless network. This GSM Modem can accept any GSM network operator SIM card and act just like a mobile phone with its own unique phone number. Advantage of using this modem will be that you can use its RS232 port to communicate and develop embedded applications. Applications like SMS Control, data transfer, remote control and logging can be developed easily. The modem can either be connected to PC serial port directly or to any microcontroller. This project is designed in such a way that a GSM modem is interfaced to the controller through serial port interface. A DC gear motor will be interfaced to the controller through driver IC L293D for opening and closing of the locker door. The GSM modem performs the task of receiving the message from the mobile and sending the messages to the mobile from the controlling unit. This arrangement will be fixed to the locker door. Whenever an authorized person wants to open the locker door he has to send predefined password message to the control system from his mobile. The GSM modem receives this message and intimates the same to the microcontroller. Now it is the job of the controller to check the received message will match with the predefined message or not, if it matches then DC gear motor is operated to unlatch the solenoid-operated lock so the locker door can be open. At the end of preset delay, the DC gear motor is operated in reverse direction and the door gets locked again. A 16X2 LCD will be interfaced to the controller to display the status of the door. If any unauthorized person want to open the locker door he send wrong password to the control system. When controller finds it is wrong password then buzzer will be on. A buzzer is also interfaced to the controller for an audio identification. This project uses regulated 5V, 500mA power supply. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac output of secondary of 230/12V step down transformer.