A multi-plate friction clutch comprising: a clutch outer which has a bottomed cylindrical shape and in which an outer cylindrical part extends along an axial direction from an outer circumferential edge of an outer bottom wall part whose centre is journaled by a rotation shaft with intermediary of a bearing; a clutch centre in which a centre cylindrical part is formed inside the outer cylindrical part and extends from a centre bottom wall part whose centre is journaled by the rotation shaft with restriction of relative rotation, the centre cylindrical part extending away from the outer bottom wall part, and the centre bottom wall part facing an inner surface of the outer bottom wall part and having a plurality of communication holes (61 h) formed at an equal distance from an axial centre; a plurality of friction plates engaging with the outer cylindrical part and a plurality of clutch plates engaging with the centre cylindrical part which are arranged alternately in the axial direction overlapping with each other in a ring-shaped space between the outer cylindrical part and the centre cylindrical part; and a pressure plate that sandwiches the friction plates and the clutch plates with the centre bottom wall part, and presses the friction plates and the clutch plates by a biasing force of a clutch spring; wherein a centre ring protrusion, projecting in a cylindrical shape from an outer surface of the centre bottom wall part, is formed at substantially the same radial position as the plurality of communication holes (61 h), a ring recess, open toward the axial centre, is formed in an inner circumferential surface of the centre ring protrusion, and the communication holes (61 h) are open so as to face the ring recess; wherein an outer ring protrusion, projecting in a cylindrical shape from the inner surface of the outer bottom wall part, is formed radially inside relative to the centre ring protrusion, and the outer ring protrusion protrudes to an axial position of the ring recess; the multi-plate friction clutch being characterized in that an axial end of the outer ring protrusion extends beyond an axial position of an opening end part of a gap in which the bearing to journal the outer bottom wall part is interposed. a clutch outer which has a bottomed cylindrical shape and in which an outer cylindrical part extends along an axial direction from an outer circumferential edge of an outer bottom wall part whose centre is journaled by a rotation shaft with intermediary of a bearing; a clutch centre in which a centre cylindrical part is formed inside the outer cylindrical part and extends from a centre bottom wall part whose centre is journaled by the rotation shaft with restriction of relative rotation, the centre cylindrical part extending away from the outer bottom wall part, and the centre bottom wall part facing an inner surface of the outer bottom wall part and having a plurality of communication holes (61 h) formed at an equal distance from an axial centre; a plurality of friction plates engaging with the outer cylindrical part and a plurality of clutch plates engaging with the centre cylindrical part which are arranged alternately in the axial direction overlapping with each other in a ring-shaped space between the outer cylindrical part and the centre cylindrical part; and a pressure plate that sandwiches the friction plates and the clutch plates with the centre bottom wall part, and presses the friction plates and the clutch plates by a biasing force of a clutch spring; wherein