An abnormality determination device for a continuously variable transmission is provided in which since the abnormality determination device which calculates a compression stiffness of a metal belt from an amplitude ratio between a variable component of the rotational speed of an input shaft and a variable component of the rotational speed of an output shaft, a phase lag that is an indicator of the difference in phase between a variable component of the rotational speed of the input shaft and a variable component of the rotational speed of the output shaft, and a belt pitch radius of a drive pulley or a driven pulley, and determines whether a metal ring has broken by comparing the compression stiffness of the metal belt with a preset reference compression stiffness.