Generally, in the previous researches, it is found that a water droplet is respectively in Wenzel and Cassie-Baxter states on hydrophilic/hydrophobic rough surfaces. And Wenzel and Cassie-Baxter equations are used to estimate the apparent contact angle on the surfaces. However, difference between measured apparent contact angle and estimated apparent contact angle with the equations is recently reported and new model to estimate apparent contact angle on rough surfaces is proposed. In this study, wetting state and apparent contact angle on the surfaces with micro-pillars should be investigated to find solution of this argument. Using the high resolution microscope, the wetting state of the D.I.water droplet on the surface with micro-pillars was visualized and apparent contact angle of the D.I.water droplet was measured. On the basis of experimental data, the equations to estimate apparent contact angle were verificated and the general wetting characteristics on the surfaces with micro-pillars are finally classified.