An arm for a working machine, comprising: an arm body having a tubular shape; and a bearing member attached to a tip portion of the arm body and adapted to pivotally support another member, wherein the bearing member includes: a boss having a cylindrical shape; and a greasing tube having: one end portion attached to a greasing hole provided on an outer peripheral surface of the boss; the other end portion attached to a side surface of the arm body; and a tube body portion connecting the one end portion and the other end portion, wherein the tube body portion is curved orienting the one end portion in a radial direction of the boss and orienting the other end portion in a direction substantially parallel to an axial direction of the boss, wherein the one end portion of the greasing tube and the tube body portion are housed inside the arm body, characterized in that the side surface of the arm body is provided with a cutout portion to which the tube body portion is inserted, the cutout portion opening toward the tip portion, and the other end portion of the greasing tube is oriented to an outside of the arm through the cutout portion and fixed to the side surface of the arm. an arm body having a tubular shape; and a bearing member attached to a tip portion of the arm body and adapted to pivotally support another member, wherein the bearing member includes: a boss having a cylindrical shape; and a greasing tube having: one end portion attached to a greasing hole provided on an outer peripheral surface of the boss; the other end portion attached to a side surface of the arm body; and a tube body portion connecting the one end portion and the other end portion, a boss having a cylindrical shape; and a greasing tube having: one end portion attached to a greasing hole provided on an outer peripheral surface of the boss; the other end portion attached to a side surface of the arm body; and a tube body portion connecting the one end portion and the other end portion, one end portion attached to a greasing hole provided on an outer peripheral surface of the boss; the other end portion attached to a side surface of the arm body; and a tube body portion connecting the one end portion and the other end portion, wherein the tube body portion is curved orienting the one end portion in a radial direction of the boss and orienting the other end portion in a direction substantially parallel to an axial direction of the boss, wherein the one end portion of the greasing tube and the tube body portion are housed inside the arm body, characterized in that the side surface of the arm body is provided with a cutout portion to which the tube body portion is inserted, the cutout portion opening toward the tip portion, and the other end portion of the greasing tube is oriented to an outside of the arm through the cutout portion and fixed to the side surface of the arm. the side surface of the arm body is provided with a cutout portion to which the tube body portion is inserted, the cutout portion opening toward the tip portion, and the other end portion of the greasing tube is oriented to an outside of the arm through the cutout portion and fixed to the side surface of the arm.