To easily recognize a moving track where a tool can move without colliding with a work and to improve the reliability of tool movement by forming the moving track of the tool by a single pattern using only a straight line and a specified circular arc.

For an interference evadable track, an orthogonally crossing point O(Xo, Yx) stipulated by an origin side straight line 100 passing through an origin position Po(Xo, Yo) and a target side straight line 102 passing through a target position Px(Xx, Yx) orthogonally crossed with the straight line is selected by a control part. Then, the circle 104 of a radius (r) is prepared with the orthogonally crossing point O as a center. The radius (r) is decided by an interference evading rate K for specifying how much the tool is to be separated from the work inside an area A formed by connecting points O, Po and Px and the straight line 106. Then, the coordinates of the intersections Q and R of the straight line 100 and the circle 104 are calculated based on the radius (r) and a 1/4 circular arc 108 is stipulated. Further, a symmetrical circular arc is prepared with the straight line 110 passing through the intersections Q and R as an axis. As a result, the moving track connected to the straight lines 100 and 102 and composed of the circular arc 112 is formed.