This study si aiming to understand the mode characteristics of a droplet under a periodic forced vibration and the detachment conditions of droplet which is placed on plate surface. In order to predict the resonance frequency of a droplet, theoretical and experimental approaches are made. A high speed camera is placed for side view and top view which is used to capture a variety of the characteristics of a droplet ? the mode shape, the detachment, the separated secondary droplet and waggling motion. The comparison between theoretical and experimental works shows no more than 18% discrepancy of predicting the resonance frequency. These differences seem to be caused by the effect of contact line friction, nonlinear wall adhesion, and the uncertainty of the experiment. In case of the lower energy input, the contact-line of the droplet is pinned and oscillation pattern is axisymmetric movement. The size of each lobe at the resonance frequency is relatively bigger than that at the neighbor frequency. A droplet at the mode 2, one of the primary mode frequencies, has a periodic movement vertically, and it has a detachment and a secondary ejection from the main droplet