In a continuously variable transmission comprising: an input shaft which is rotated by a drive source; an output shaft which takes out a driving force attributing the rotation of the input shaft; and a variator and a planet gear mechanism which are arranged between the input shaft and the output shaft, the variator having a clutch which provides a first mode in which a driving force circulation is carried out, and a second mode in which the driving force circulation is not carried out, the speed of a first driving force transmitting system which is inputted to the planet gear mechanism through the variator and the speed of a second driving force transmitting system which is inputted to the planet gear mechanism directly, not through the variator are detected with first and second speed detecting sensors, and, upon detection of the substantial coincidence in the ratio of speed of the first and second driving force transmitting shafts, the mode switching operation is carried out with the clutches.