SCREW JOINT FOR OIL WELL PIPE

Provided is a screw joint for an oil well pipe in which an efficient screw length of a joint portion is achieved, and a processing time and a construction time are reduced. The present invention provides a screw joint for an oil well pipe of an integral type, including a pin that is provided with a male screw portion which is a male taper screw, at one end of a steel pipe; and a box that is provided with a female screw portion which is a female taper screw fitted to the male screw portion, at one end of the steel pipe, in which a structure, in which the pin and the box are in metal contact with each other to seal a fluid, is provided at least at one place of a seal portion on an outer peripheral surface side of a pipe end side of the pin and a seal portion on an inner peripheral surface side of a pipe end side of the box, in which a minimum value Lmin (mm) of a screw length L (mm) in screw rows of the male taper screw and the female taper screw is defined by expression (1), and in which the screw length L (mm) in the screw rows satisfies expression (2). Lmin=t×D−t/αt×Dt/√3×jointefficiencyLmin×1.0≤L≤Lmin×2.5