This paper proposes the interactive lecture system based on mixed reality using a transparent display that enables interaction with the users watching the display. This system unlike existing remote video lectures, will allow students to participate progressively in the lectures by enabling the interaction between the instructor and students. Furthermore, this system also improves the reality in such a way that, during the visualization of the real-time video lectures on the transparent display, it seems that the instructor is in the same place with the students. This paper experiments and implements the proposed system based on the transparent display, 2D camera, and 3D sensors.