Self-aligning roller bearing

A self-aligning roller bearing configured to support a main shaft of a wind power generator, the self-aligning roller bearing comprising:

• an inner ring;
• an outer ring;
• two rows of rollers interposed between a raceway surface of the inner ring and a raceway surface of the outer ring;
• and a retainer configured to retain the respective rows of the rollers, wherein the raceway surface of the outer ring has a spherical shape continuously extending over the two rows of the rollers, each of the rollers having an outer peripheral surface having a cross-sectional shape matching the raceway surface of the outer ring,
• each of the rollers has a DLC coating having a multilayer structure on the outer peripheral surface,
• 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, and
• 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.