A method of manufacturing a mirror includes a first step of arranging, on a substrate, a shape adjusting layer having a layer thickness which changes by heat, a second step of arranging, on the shape adjusting layer, a reflection layer including a first layer, a second layer, and a barrier layer which is arranged between the first layer and the second layer, and prevents a diffusion of a material of the first layer and a material of the second layer, and a third step of bringing a shape of the reflection layer close to a target shape by changing a layer thickness profile of the shape adjusting layer after the second step, the third step including a process of partially annealing the shape adjusting layer.