A planetary-type epicyclic gearing comprising: a sun gear having a row of external teeth; a plurality of planetary gears disposed around the sun gear, each of the plurality of planetary gears having a row of external teeth which mesh with the external teeth of the sun gear; a planetary carrier at which the plurality of planetary gears are rotatably provided, the planetary carrier being rotatable around the sun gear together with the plurality of planetary gears; and a ring gear having a pair of rows of internal teeth (4a, 4b) which mesh with the external teeth of the plurality of planetary gears, the plurality of planetary gears being arranged inward of the ring gear, wherein the planetary carrier includes an oil feeding passage which feeds lubricating oil to at least one of the plurality of planetary gears, the ring gear is a double helical gear in which the pair of rows of internal teeth (4a, 4b) are arranged in a direction of an axis line of the ring gear and the internal teeth of one of the rows and the internal teeth of the other of the rows are inclined in different directions, and the ring gear is unrotatable, characterized in that: the ring gear includes at least one discharge passage, the at least one discharge passage includes an inlet-side portion and an outlet-side portion, the inlet-side portion being close to an inlet configured to open in a region between the pair of rows of internal teeth (4a, 4b) at an inner peripheral surface of the ring gear, and the outlet-side portion being close to an outlet configured to open in a region of an outer peripheral surface of the ring gear, the inlet-side portion is formed at the ring gear so that the inlet-side portion is inclined in a rotation direction of the planetary carrier, with respect to a reference line extending in a radial direction of the ring gear, and rotation of the planetary carrier and the planetary gears around the sun gear causes the lubricating oil to flow along the inner peripheral surface of the ring gear in the same direction as a direction of the rotation of the planetary carrier and to discharge outside of the ring gear through the discharge passage. a sun gear having a row of external teeth; a plurality of planetary gears disposed around the sun gear, each of the plurality of planetary gears having a row of external teeth which mesh with the external teeth of the sun gear; a planetary carrier at which the plurality of planetary gears are rotatably provided, the planetary carrier being rotatable around the sun gear together with the plurality of planetary gears; and a ring gear having a pair of rows of internal teeth (4a, 4b) which mesh with the external teeth of the plurality of planetary gears, the plurality of planetary gears being arranged inward of the ring gear, wherein the planetary carrier includes an oil feeding passage which feeds lubricating oil to at least one of the plurality of planetary gears, the ring gear is a double helical gear in which the pair of rows of internal teeth (4a, 4b) are arranged in a direction of an axis line of the ring gear and the internal teeth of one of the rows and the internal teeth of the other of the rows are inclined in different directions, and the ring gear is unrotatable, characterized in that: the ring gear includes at least one discharge passage, the at least one discharge passage includes an inlet-side portion and an outlet-side portion, the inlet-side portion being close to an inlet configured to open in a region between the pair of rows of internal teeth (4a, 4b) at an inner peripheral surface of the ring gear, and the outlet-side portion being close to an outlet configured to open in a region of an outer peripheral surface of the ring gear, the inlet-side portion is formed at the ring gear so that the inlet-side portion is inclined in a rotation direction of the planetary carrier, with respect to a reference line extending in a radial direction of the ring gear, and rotation of the planetary carrier and the planetary gears around the sun gear causes the lubricating oil to flow along the inner peripheral surface of the ring gear in the same direction as a direction of the rotation of the planetary carrier and to discharge outside of the ring gear through the discharge passage. the ring gear includes at least one discharge passage, the at least one discharge passage includes an inlet-side portion and an outlet-side portion, the inlet-side portion being close to an inlet configured to open in a region between the pair of rows of internal teeth (4a, 4b) at an inner peripheral surface of the ring gear, and the outlet-side portion being close to an outlet configured to open in a region of an outer peripheral surface of the ring gear, the inlet-side portion is formed at the ring gear so that the inlet-side portion is inclined in a rotation direction of the planetary carrier, with respect to a reference line extending in a radial direction of the ring gear, and rotation of the planetary carrier and the planetary gears around the sun gear causes the lubricating oil to flow along the inner peripheral surface of the ring gear in the same direction as a direction of the rotation of the planetary carrier and to discharge outside of the ring gear through the discharge passage.