A railcar bogie axle box suspension axle beam includes an end portion d at a tip end, a tubular portion at the end portion and being open at both car width direction sides. The tubular portion includes: a first semi-tubular portion integrally formed with a main body portion; a second semi-tubular portion brought into contact with the first semi-tubular portion from one side in the car longitudinal direction; and a bolt fastening the second semi-tubular portion to the first. The first semi-tubular portion includes: a flat opposing surface contacting the second semi-tubular portion; and a hole into which the bolt is inserted. The second semi-tubular portion includes: a flat opposing surface contacting with the first semi-tubular portion surface; a flat machining reference surface formed at an opposite side of the opposing surface; and a hole extending in a direction perpendicular to the opposing surface, the bolt inserted into the hole.