A micro disk laser having a greater strength of oscillation in one direction than in another direction and unidirectionally oscillating includes a micro disk having an oval shape corresponding to a modified ellipse obtained by changing a length of a short axis of an ellipse according to a position of a long axis while lengths of first and second side portions of the long axis are fixed in the ellipse, the ellipse having the long axis and the short axis having a different length than the long axis.
