To reduce assembly man-hours of a planetary gear device by devising a structure of a carrier, disclosed is a carrier of a planetary gear device 1 is formed with a gear housing space for housing a sun gear and a planetary gear. The gear housing space is formed between a pair of gear support parts rotatably supporting the planetary gear by a gear support shaft. The pair of gear support parts are integrally connected by a plurality of beams. The beam has a virtual plane orthogonal to a rotation axis of the sun gear as an x-y plane, and a radial direction of a direction extending radially from the rotation axis along the x-y plane is formed along a radial direction at a radially outer position of the sun gear. The planetary gear is located between the beams.