A speed change gear includes: a housing that has internal gears having different inside diameters; and a plurality of change gear units that are respectively in mesh with the plurality of internal gears and that change the speed of rotation from an input shaft to an output shaft. Each of the change gear units includes a rotating member that has one of a pin protruding in a direction along an input/output axis and an insertion hole; an eccentric member that centers on an eccentric axis that is eccentric with respect to the input/output axis; and an oscillating member that oscillatingly rotates as the eccentric member rotates about the input/output axis.