To provide, as a tool for harvesting the ovary living inside the shell of sea urchin by cracking the shell, a device for creating a hole in the shell of sea urchin with which the shell of sea urchin is cracked in an operation of little labor without deforming the ovary and scattering the guts inside the shell.

A cylindrical body 1 composed of a thin metal sheet, a tool for creating a round hole C in the shell B of sea urchin A, includes: an opening 3 with a bottom 2; a handle 5 composed of resin material which is integrated by a stop shaft 4 at the center of the bottom; and, in addition, triangle blades 7 having the pointed tips 6, 6a, 6b and 6c with an acute angle D arranged around the circumference of the opening. The triangle blades are formed so that each pair of blades opposed on the circumference have an equal height h of tips and the blade pairs have a gradual difference (a) in height.