In this paper, we discuss pointing gesture estimation in the context of Human Robot Interaction (HRI). Pointing gesture provides and utilizes information in Kukanchi (Interactive Human Space Design and Intelligence) more natural than other conservative method like keyboard or mouse. Therefore, we design a user interface adopting pointing gesture to manipulate objects and robot naturally in 3D space. Initially, human posture is tracked. Later, the information is used to detect the dynamic pointing gesture using our proposed method which is Hidden Markov Model (HMM). Preliminary experiment shows the average angular error of pointing direction is less than seven degrees.