Long period of oil palm trees life cycle, which takes around 25 years, would relate to yearly production cost requirement. This mean that input prices change together with age stage of the trees and land type would influence the production cost value. Therefore for economically rational farmers, their demand for inputs would increase (or decrease) as the price decrease (or increase), ceteris paribus. In the ouput perspective, the demand of inputs would increase as the oil palm fresh fruit bunch (FFB) increase, and its would decrase as the output price deacrease, ceteris paribus. In order to gain maximum profit, farmers have to apply the inputs combination at optimal level. This phenomenon is interesting to be studied further.