PURPOSE: A gear box capable of changing the angle of a rotary shaft is provided to easily modify the location of an input shaft by rotation of a bracket. CONSTITUTION: An input unit is prepared in a housing (10) and includes a power shaft and a first gear. A power transmission unit includes a second gear and an idle shaft rotating by being engaged with the second gear. An output unit includes a third gear and an output shaft (320) rotating by being engaged with the third gear. The third gear is directly engaged with the first gear or is engaged with the second gear rotated by the input unit. A direction conversion unit controls a location of the input unit to make the first gear be selectively engaged with one of the second gear or the third gear.
