A method of manufacturing a group 13 nitride crystal includes a crystal growth process to form the group 13 nitride crystal by growing the group 13 nitride crystal having a hexagonal crystal structure from a seed crystal which is a gallium nitride crystal having a hexagonal crystal structure in which a length “L” in a c-axis direction is 9.7 mm or more, and a ratio L/d of the length “L” to a crystal diameter “d” in a c-plane is larger than 0.813. The crystal growth process includes a process of forming an outer periphery containing a {10-10} plane and an outer periphery containing a {10-11} plane at side surfaces of the group 13 nitride crystal, and forming an outer periphery containing a {0001} plane at a bottom surface of the group 13 nitride crystal.