PURPOSE: To draw a draw of a required curvature in a small space easier and protect the surface of a signboard and others from damage.

CONSTITUTION: One ends of a pair of arms 1a, 1b are linked together rotatably by a hinge 2 and the ends of a elastic ruler 3 are connected to the other ends of the arms 1a, 1b. One end of an angle retaining plate 5 is fitted to one arm 1a and multiple insertion holes 7 are formed on the other end of the angle retaining plate 5 in a longitudinal direction. An angle 6 between the arms 1a and 1b can be fixed at a required angle by engaging the insertion hole 7 and a pin 8 fixed to the other arm 1b. The ruler 3 is deflected to the curvature of an intended curve, the arms 1a, 1b are fixed as they are, and a line is drawn along the outside or inside periphery of the ruler 3.