PROBLEM TO BE SOLVED: To secure durability of a bearing which supports a driving portion of a joint of a multijoint robot arm and concurrently achieve downsizing of the joint of the multijoint robot arm.SOLUTION: A joint driving mechanism 4 of a multijoint robot arm includes: a motor 41 a speed reducer 43 which is connected with the motor 41 and has an output shaft corresponding with a rotation axis of the joint an output member 6 connected with the output shaft of the speed reducer 43 a cross roller bearing 434 rotatably supporting the output member 6 and a needle bearing 7 including an outer ring part 71, an inner ring part 72, and needles 73 provided at the outer ring part 71. At least one of the outer ring part 71 and the inner ring part 72 is connected with the output member 6. The inner ring part 72 and the needles 73 provided at the outer ring part 71 are arranged so as to be spaced a predetermined distance apart from each other.SELECTED DRAWING: Figure 5【課題】多関節ロボットアームの関節の小型化を図りながら、多関節ロボットアームの関節の駆動する部分を支持する軸受の耐性を確保すること。【解決手段】この多関節ロボットアームの関節駆動機構4は、モータ41と、モータ41に接続され、出力軸が関節の回転軸線と一致する減速機43と、減速機43の出力軸に接続された出力部材6と、出力部材6を回転可能に支持するクロスローラベアリング434と、外輪部71と、内輪部72と、外輪部71に設けられた複数のニードル73とを含むニードルベアリング7とを備える。外輪部71および内輪部72のうち一方は、出力部材6に接続されており、内輪部72と、外輪部71に設けられたニードル73とは、所定の間隔を隔てて離間して配置されている。【選択図】図5
