This Final Project Making, aims to apply microcontroller technology based on ATMega8535 to design and make security system tool layered in the safe. This can be achieved by creating tools that can be applied to devices that are automatically systemized. For example, the current security system on the safe is still manual, so people can easily access it. The manual process is perceived as less efficient in this digital era. The working principle of this tool is Input the first Password. The first password can be entered using the keypad is available, this first password is fixed and predefined. When the first password is entered, the microcontroller will process the existing Password with the Password input on the keypad. If the password is wrong then the buzzer will sound and red will turn on, when the password is wrong 5 times then the program will freeze. If Password is correct then gsm module will send second password to owner in sms, this second password will be random. When the second password has been obtained the owner can use the password to open the safe. If the second password is correct then the green led light will be alive and selenoid will move unlock, and if password is wrong then buzzer will sound and red will turn on, if password entered wrong 5 times then program will freeze.
Keywords: Microcontroller ATMega8535, LCD, Keypad, Selenoid Doorlock, Buzzer, Modul GSM.