To propose a planetary gear device having a mounting structure in which mounting of a catch plate to a carrier is carried out easily and at a low cost.

In the planetary gear device, a plurality of projections are formed to a carrier cover constituting the carrier, the projections and the carrier are fitted, and at the same time, the catch plate is fixed to the carrier cover by caulking the projections. As a result, formation of a groove or the like to fit the catch plate on the carrier cover side is not required, and working man-hours and manufacturing costs is reduced.