A security system consisted of an infrared sensor and PLD(Programmable Logic Device) was fabricated to prevent an intruder. The fabricated system detect the intruder using infrared sensor and has password key pad to permit someone to enter the house and office. The control circuit of the system is designed by VHDL(Very high speed integrated Hardware Description Language). The system was demonstrated in various conditions and the output signals were displayed in LCD, LED, buzzer and so on. This designed system in this paper has a advantage to supplement additional function with ease.