Abstract: A needle employs a three-stair-stepped structure including a front-end small diameter part, an intermediate part, and a large diameter part. The front-end small diameter part and the intermediate part are in fluid communication with each other by a first tapered part, and the intermediate part and the large diameter part are in fluid communication with each other by a second tapered part. The internal diameter of the front-end small diameter part is made so as to be equal to or greater than 0.35 mm based on the allowable deformation level of a cumulus oocyte complex, the outer diameter is made so as to be equal to or smaller than 0.7 mm based on the size of a small follicle, and the inclination angle of the inclined acicular end, and the length is made so as to be 10-25 mm based on the size of a dominant follicle.