A control device of a continuously variable transmission for a vehicle has a pair of variable pulleys and a transmission belt, and the control device respectively controls input-side and output-side thrust forces of input-side and output-side variable pulleys to set an actual gear ratio to a target gear ratio, prevents a slip of the transmission belt, and determines a lowest-speed-side gear ratio. When it is determined that a detection value of a rotation speed for calculating the actual gear ratio does not reflect an actual rotation speed, target input-side and output-side thrust forces are set to be target thrust forces for maintaining the lowest-speed-side gear ratio and preventing the slip of the transmission belt, and based on whether the actual gear ratio is already the lowest-speed-side gear ratio, values of the input-side and output-side thrust forces are changed for obtaining the target thrust forces.