Provided is a self-aligning roller bearing for supporting a main shaft of a wind power generator, the self-aligning roller bearing including an inner ring, an outer ring, two rows of rollers, and retainers. Each of the rollers has an outer peripheral surface formed with a DLC coating having a multilayer structure. The DLC coating has a film thickness of 2.0 μm or larger. A base material of each of the rollers has an external surface having a surface roughness of Ra≤0.3 and RΔq≤0.05. The DLC coating having the multilayer structure includes layers having stepwisely increasing film hardnesses such that a layer situated closer to outside has a higher hardness.