Single crystals of NdBa 2 Cu 3 O 7 - δ (Nd123) have been successfully grown by the top-seeded solution-growth (TSSG) method in 1%, 21% and 100% oxygen partial pressure atmosphere ((P(O 2 )= 0.01 atm, P(O 2 ) = 0.21 atm and P(O 2 )= 1.00 atm). Ba Cu O solvent with a Ba to Cu ratio of 3:5 was used in a Nd 2 O 3 crucible. Nd is supplied by the reaction between the molten solvent and the Nd 2 O 3 crucible. Compositions of Nd123 single crystals grown in different oxygen partial pressure atmospheres were analyzed by inductivity coupled plasma atomic emission spectrometry (ICP-AES) and confirmed to be Nd:Ba:Cu = 1.01:1.97:3.00 for P(O 2 ) = 0.01 atm, Nd:Ba: Cu = 1.07: 1.95:3.00 for P(O 2 ) = 0.21 atm and Nd:Ba:Cu = = 1.10: 1.90:3.00 for P(O 2 ) = 1.00 atm, respectively. The Nd123 single crystals grown in different oxygen partial pressure atmospheres were annealed in a pure oxygen gas flow, and the temperature dependence of the DC magnetization for these crystals was measured using a superconducting quantum interference device (SQUID) magnetometer. The Nd123 single crystal grown in P(O 2 ) = 0.01 atm, and annealed at 340 o C for 200 h showed a steep superconductive transition at 96 K. On the other hand, the Nd123 crystal grown in P(O 2 ) = 0.21, 1.00 atm and, annealed at 340 o C for 200 h exhibited a broad transition at 92 K for P(O 2 ) = 0.21 atm and at 88 K for P(O 2 ) = 1.00 atm, respectively. Therefore for Nd123 single crystal production with high quality superconductive characteristics, a low oxygen partial pressure atmosphere during crystal growth is found to be effective for minimizing the substitution of Nd ions into Ba sites.