The present invention relates to a microdisk laser with a unidirectional generation property, and more particularly, to a microdisk laser designed in the form of a triangle, wherein the incident angles of portions of a laser beam at two upper sides of the triangle are greater than a critical angle to cause total reflection, so that the laser beam generates with directionality toward the base of the triangle. To this end, in the microdisk laser with the unidirectional generation property, the laser takes the shape of a triangle with two upper sides and the base and the two upper sides have their lengths greater than or equal to that of the base. Respective vertexes of the triangle or some of the vertexes are curved, and incident angles of portions of a laser beam at the two upper sides of the triangle are greater than a critical angle to cause total reflection, so that the laser beam generates with directionality toward the base of the triangle.