There is provided a method for fabricating a gallium nitride crystal with low dislocation density, high crystallinity, and resistance to cracking during polishing of sliced pieces by growing the gallium nitride crystal using a gallium nitride substrate including dislocation-concentrated regions or inverted-polarity regions as a seed crystal substrate. Growing a gallium nitride crystal 79 at a growth temperature higher than 1,100° C. and equal to or lower than 1,300° C. so as to bury dislocation-concentrated regions or inverted-polarity regions 17a reduces dislocations inherited from the dislocation-concentrated regions or inverted regions 17a, thus preventing new dislocations from occurring over the dislocation-concentrated regions or inverted-polarity regions 17a. This also increases the crystallinity of the gallium nitride crystal 79 and its resistance to cracking during the polishing.