In this study, a data acquisition system that recording of the movement of diaphragm was designed. At this microcontroller circuit, an acceleration which has ability to define position by using 3-axis Cartesian coordinate systems was used. The information obtained from the sensor, saved to the internal eeprom and transferred to the computer via USB. These data which were received to the computer, were grouped to the axis and plotted by the computer program which is developed at C # programming language. Patient position can be detected as well as the breathing signals form corresponding graph. Hence, it is easy to monitor, at which position and at which duration the patient is making effort. This ability gives us advantage to use this system for sleep apnea study. Meantime, the data transferred to the computer can also be saved in a text file in order to use in Matlab program to investigate both time and frequency analyzes. Since the developed system is portable, it can be used for a number of other study and research.