Conventional sensor-based navigation algorithms for mobile robot such as Tangent Bug algorithm work only for stationary obstacles. When a mobile robot is operated in more general unknown environment, moving obstacles such as human should also be considered. In this paper, a navigation algorithm which works for moving obstacles and stationary ones with unknown environment is proposed, using a new idea that distinguishes moving obstacles from stationary ones with distance information by sensor of mobile robot. The idea is based on the definition of an inclination angle on the wall surface that is called the wall surface angle. The wall surface angle of each step is accumulated while following the boundary. When the difference between the total accumulated angle and the initial one that is the rotation angle of the robot is over 2π radian, currently following obstacle is recognized as a moving obstacle. According to this idea with Tangent Bug algorithm for stationary obstacles, the navigation algorithm for moving convex shaped obstacles is constructed. In this paper the effectiveness of this algorithm for moving obstacles is shown by simulations.