One of aspects of the present invention is to provide a medical lancet, which includes a first ascending region, a descending region, and a second ascending region subsequently and integrally formed of biodegradable material. Those regions extend from a point of the lancet in a predetermined direction, and each of the regions having triangular cross sections taken along any planes perpendicular to the predetermined direction. The first and second ascending regions have the triangular cross sections of which area monotonically increases as being away from the point. Also, the descending region has the triangular cross sections of which area monotonically decreases as being away from the point. The first and second ascending regions have the largest cross section having substantially the same size and shape to each other.