A filling method is disclosed in which a robot arm moves a discharge port to a first position in a first recessed portion, and at the first position, a discharge of the viscous material is started. After the discharge of the viscous material is started, the discharge of the viscous material is stopped. In a state where the discharge of the viscous material is stopped, the robot arm moves the discharge port above the first recessed portion. In a state where the discharge of the viscous material is stopped, the robot arm moves the discharge port to a second position in the first recessed portion by moving the discharge port in the horizontal direction and then moving the discharge port downward along the vertical direction, or by moving the discharge port obliquely downward. At the second position, the discharge of the viscous material from the discharge port is started.