To reduce the fluctuation of wind power output by installing storage batteries to wind power generation, accurate estimation of wind power is indispensable. Calculation based on Power Curve, general method to estimate wind power output, often causes unavoidable error due to influences of time fluctuation of wind speed and direction. Therefore, we propose to apply Just-In-Time (JIT) Modeling to the estimation and the forecast of wind power output. JIT Modeling has the advantage that the algorithm is relatively simple. Compared with another non-linear modeling method, we confirmed the validation of JIT Modeling against the estimation and forecasts of wind power output through computational simulations.