A dual mode continuously variable transmission (DMCVT), which can maintain advantages of a reducer operated in low-speed running mode and makes the diameter ratio of variable speed pulleys in high-speed transmission mode act as a reducer, thus improving durability and energy efficiency of the CVT. The DMCVT has a drive variable speed pulley mounted on an input shaft connected to an engine, a driven variable speed pulley mounted on an output shaft and receiving a rotatory force from the drive pulley through a belt, a drive shaft, first and second mode output gears mounted on the output shaft, first and second mode drive gears mounted on the drive shaft and gearing into the first and second mode output gears, respectively, and a synchro selector selectively engaging with a gear of one of the drive and driven shafts.