Abstract: An end portion machining apparatus capable of achieving an increase in both productivity and accuracy. The apparatus comprises a rotatable chuck which holds the vicinity of one end of a tubular good LP, a thread cutting machine 12 which is installed in the vicinity of the chuck and which has a machining tool which can be adjusted in position with respect to one end portion of the tubular good LP rotating with the chuck, and a support device 13 which supports the other end portion of the rotating tubular good LP while following the tubular good LP. The support device 13 comprises four support rollers 13a, 13b, 13c, and 13d which form pairs installed on both sides of the tubular good LP, each pair comprising an upper and lower roller, and air cylinders 13e and 13f which can individually move the pairs of support rollers 13a, 13b and 13c, 13d each comprising an upper and lower roller into and out of contact with the tubular good LP.