Affords methods of manufacturing bulk III-nitride crystals whereby at least the surface dislocation density is low globally. The present III-nitride crystal manufacturing method includes: a step of preparing an undersubstrate (1) containing a III-nitride seed crystal, the III-nitride seed crystal having a matrix (1s), and inversion domains (1t) in which the polarity in the directions is inverted with respect to the matrix (1s); and a step of growing a III-nitride crystal (10) onto the matrix (1s) and inversion domains (it) of the undersubstrate (1) by a liquid-phase technique; and is characterized in that a first region (10s), being where the growth rate of III-nitride crystal (10) growing onto the matrix (1s) is greater, covers second regions (10t), being where the growth rate of III-nitride crystal (10) growing onto the inversion domains (1t) is lesser.