A duplex stainless seamless steel pipe comprising: a chemical composition consisting of, in mass%, C: 0.030% or less, Si: 0.20 to 1.00%, Mn: 0.50 to 7.00%, P: 0.040% or less, S: 0.0100% or less, Cu: 1.80 to 4.00%, Cr: 20.00 to 28.00%, Ni: 4.00 to 9.00%, Mo: 0.50 to 2.00%, Al: 0.100% or less, N: 0.150 to 0.350%, V: 0 to 1.50%, Nb: 0 to 0.100%, Ta: 0 to 0.100%, Ti: 0 to 0.100%, Zr: 0 to 0.100%, Hf: 0 to 0.100%, Ca: 0 to 0.0200%, Mg: 0 to 0.0200%, B: 0 to 0.0200%, and rare earth metal: 0 to 0.200%, with the balance being Fe and impurities, and a microstructure consisting of 30.0 to 70.0% of ferrite in volume ratio and austenite as the balance, as measured according to the method described in the description, wherein when a pipe axis direction of the duplex stainless seamless steel pipe is defined as an L direction and a pipe radius direction of the duplex stainless seamless steel pipe is defined as a T direction, in a square observation field of view region which includes a center portion of wall thickness of the duplex stainless seamless steel pipe, and whose side extending in the L direction is 1.0 mm long and whose side extending in the T direction is 1.0 mm long, four line segments, which extend in the T direction, which are arranged at equal intervals in the L direction of the observation field of view region, and which divide the observation field of view region into five equal parts in the L direction, are defined as T1 to T4, four line segments, which extend in the L direction, which are arranged at equal intervals in the T direction of the observation field of view region, and which divide the observation field of view region into five equal parts in the T direction, are defined as L1 to L4, and an interface between the ferrite and the austenite in the observation field of view region is defined as a ferrite interface, a number of intersections NT, which is a number of intersections between the line segments T1 to T4 and the ferrite interface, is 40.0 or more, as measured according to the method described in the description, and a number of intersections NL, which is a number of intersections between the line segments L1 to L4 and the ferrite interface, as measured according to the method described in the description, and the number of intersections NT satisfy Formula. NT / NL ≥ 2.0 a chemical composition consisting of, in mass%, C: 0.030% or less, Si: 0.20 to 1.00%, Mn: 0.50 to 7.00%, P: 0.040% or less, S: 0.0100% or less, Cu: 1.80 to 4.00%, Cr: 20.00 to 28.00%, Ni: 4.00 to 9.00%, Mo: 0.50 to 2.00%, Al: 0.100% or less, N: 0.150 to 0.350%, V: 0 to 1.50%, Nb: 0 to 0.100%, Ta: 0 to 0.100%, Ti: 0 to 0.100%, Zr: 0 to 0.100%, Hf: 0 to 0.100%, Ca: 0 to 0.0200%, Mg: 0 to 0.0200%, B: 0 to 0.0200%, and rare earth metal: 0 to 0.200%, with the balance being Fe and impurities, and a microstructure consisting of 30.0 to 70.0% of ferrite in volume ratio and austenite as the balance, as measured according to the method described in the description, wherein when a pipe axis direction of the duplex stainless seamless steel pipe is defined as an L direction and a pipe radius direction of the duplex stainless seamless steel pipe is defined as a T direction, in a square observation field of view region which includes a center portion of wall thickness of the duplex stainless seamless steel pipe, and whose side extending in the L direction is 1.0 mm long and whose side extending in the T direction is 1.0 mm long, four line segments, which extend in the T direction, which are arranged at equal intervals in the L direction of the observation field of view region, and which divide the observation field of view region into five equal parts in the L direction, are defined as T1 to T4, four line segments, which extend in the L direction, which are arranged at equal intervals in the T direction of the observation field of view region, and which divide the observation field of view region into five equal parts in the T direction, are defined as L1 to L4, and an interface between the ferrite and the austenite in the observation field of view region is defined as a ferrite interface, a number of intersections NT, which is a number of intersections between the line segments T1 to T4 and the ferrite interface, is 40.0 or more, as measured according to the method described in the description, and a number of intersections NL, which is a number of intersections between the line segments L1 to L4 and the ferrite interface, as measured according to the method described in the description, and the number of intersections NT satisfy Formula. NT / NL ≥ 2.0