A method of manufacturing a nitride substrate includes the following steps. Firstly, a nitride crystal is grown. Then, the nitride substrate including a front surface is cut from the nitride crystal. In the step of cutting, the nitride substrate is cut such that an off angle formed between an axis orthogonal to the front surface and an m-axis or an a-axis is greater than zero. When the nitride crystal is grown in a c-axis direction, in the step of cutting, the nitride substrate is cut from the nitride crystal along a flat plane which passes through a front surface and a rear surface of the nitride crystal and does not pass through a line segment connecting a center of a radius of curvature of the front surface with a center of a radius of curvature of the rear surface of the nitride crystal.