This paper proposes a human body posture estimation method from image using ANN. The input feature vector of the ANN is composed with the result of analyzing a human silhouette image and the output vector of the ANN indicates the 2D coordinates of the human body's significant points, such as head, shoulders, hands, elbows, knees, and feet. The estimated results are optimized and tracked by using Kalman filter. The proposed estimation method is implemented on a personal computer and runs in real-time. Experimental results show both the feasibility and the effectiveness of the proposed method for estimating human body postures.