Rehabilitation exercises which maintain a patient's interest and quantitative evaluation of rehabilitation are required. To solve these problems, we have developed a haptic device system. This system consists of a haptic device, a display, a computer, and software for a training program. When users move the grip, the haptic device provides a virtual force, either assisting the movement of their arm or working against it. To investigate the functional effect of this system using a training program, we measured the grip position, velocity, force on the grip, and electromyographic (EMG) activites during a reaching task for five healthy subjects. Spatio-temporal patterns of both the velocity and grip force, the accuracy of the grip trajectories, and the EMG patterns were similar in all subjects. These results suggested that the EMG activities were improved by applying the virtual force to the grip. These results can be used for the development of rehabilitation training programs and evaluation methods.