This thesis deals with the question of electronic security systems. In the forepart are described electronic security system components such as keyboards, detectors, alarm devices etc. Various methods of security or de-security of properties, trespassing and other events detection methods, and ways of alarm calling are described there too. The next part of the master’s thesis focuses on the construction of an alarm system which is designed for security of a common-size flat with one entry. The system manages to control up to four movement detectors. The operation of the system is handled by a 16 button keyboard, and easy orientation is provided thanks to a liquid crystal display. The alarm is signaled by an indoor alert siren, however, othe...