A program changing device includes a sequence interchanging unit for interchanging plural teaching points in a teaching sequence such that total movement time of a robot becomes smaller than that when the robot is moved in line with an initial teaching sequence of the teaching points, a calculating unit for calculating difference amounts between the initial teaching points and a trajectory of the robot that is obtained by executing an after-interchanged operational program by simulation, a position adjusting unit for adjusting positions of the teaching points of the after-interchanged operational program until the difference amounts become equal to or smaller than a predetermined allowable value, and a teaching point changing unit for changing the adjusted teaching points to be the initial teaching points when cycle time of the after-interchanged operational program including the adjusted teaching points is longer than initial cycle time.