PURPOSE: To write an ellipse by using an inclined disk as a ruler.

CONSTITUTION: A strut 2 is fixed to a base mount 1, and a disk fixing pipe 3, a packing 4, a disk 5, a packing 4, and a disk fixing pipe 3 are mounted thereon in this order and fixed. Thereafter, a piston 7 and an arm 8 are mounted on a vertical ruler 6, the piston 7 is inserted to a shaft 9, a coil spring 10 is inserted and fixed, a handle 11 and a pressing knob 12 are installed, and this is inserted to the strut 2 through a cushion spring 13 and fixed. Then, a writing utensil 15 is installed to a hand 14. A disk 5 is constructed so as to be inclinedly fixed to the strut 2. An ellipse can be written by gripping and depressing the pressing knob 12 and rotating the handle 11. Various types of ellipses can be drawn with high accuracy by changing the inclined angle of the disk.