Background: People these days use smartphone extensively as a means of diverse social activities, but excessive use of it has also created increasing forward head posture (FHP) with neck pain. To improve this FHP, neck stabilization exercise is necessary. Objectives: This study was to investigate the effects of stabilization exercise using biofeedback on FHP subjects with neck pain. Design: A non-randomized, controlled intervention study. Methods: This study chose 18 college students in their 20s whose neck disability index (NDI) was equal to or higher than 10 and cranio-vertebral angle indicated FHP as experimental group. The control group selected 18 persons with no neck pain and a normal range of cranio-vertebral angle. The stabilization movement was performed by applying three phases of pressure, with low of 20 mmHg, intermediate of 25 mmHg, and high of 30 mmHg, using the Stabilizer. To check the effects of stabilization exercise according to pressure, the circumference of deep neck muscles was measured with ultrasonic waves, and the activity of surface muscle of sternocleidomastoid (SCM) was measured using electromyography (EMG). Results: When the circumference of the deep neck flexor was analyzed according to the pressure change during stabilization exercise, the experimental group showed increase at all pressures. The activity of the SCM of the surface muscle increased in both groups as the pressure increased. Conclusion: The application of stabilization exercise was found to be more effective on forward head posture subjects with neck pain at lower pressures.