A self-aligning roller bearing comprising: an outer ring having an outer raceway surface that is a recessed curve on an inner periphery of the outer ring ; an inner ring having two rows of inner raceway surfaces that are recessed curves side by side on an outer periphery of the inner ring and having a rib portion at each axially outward end; a plurality of spherical rollers disposed between the outer raceway surface and the inner raceway surface in two rows side by side; a cage having a plurality of pockets that accommodate the spherical rollers to hold each row of the spherical rollers at intervals in a circumferential direction; and a guide ring disposed between the cage and the inner ring as well as between the two rows of the spherical rollers , wherein in a longitudinal section including a center line (CL) of the spherical roller and an axis (O) of the self-aligning roller bearing , a clearance X between an outer end surface of the spherical roller on an axially outer side of the self-aligning roller bearing and the rib portion , and a clearance Y between an inner end surface of the spherical roller on an axially inner side of the self-aligning roller bearing and the guide ring have a relation of X < Y, characterized in, that the cage includes an annular member disposed radially outward of the guide ring as well as between the two rows of the spherical rollers , and in the longitudinal section including the center line (CL) of the spherical roller and the axis (O) of the self-aligning roller bearing , when a clearance between the axially outer side surface of the annular member and the inner end surface of the spherical roller is regarded as a clearance Z, the clearances Y and Z have a relation of Y < Z. an outer ring having an outer raceway surface that is a recessed curve on an inner periphery of the outer ring ; an inner ring having two rows of inner raceway surfaces that are recessed curves side by side on an outer periphery of the inner ring and having a rib portion at each axially outward end; a plurality of spherical rollers disposed between the outer raceway surface and the inner raceway surface in two rows side by side; a cage having a plurality of pockets that accommodate the spherical rollers to hold each row of the spherical rollers at intervals in a circumferential direction; and a guide ring disposed between the cage and the inner ring as well as between the two rows of the spherical rollers , wherein in a longitudinal section including a center line (CL) of the spherical roller and an axis (O) of the self-aligning roller bearing , a clearance X between an outer end surface of the spherical roller on an axially outer side of the self-aligning roller bearing and the rib portion , and a clearance Y between an inner end surface of the spherical roller on an axially inner side of the self-aligning roller bearing and the guide ring have a relation of X < Y, characterized in, that the cage includes an annular member disposed radially outward of the guide ring as well as between the two rows of the spherical rollers , and in the longitudinal section including the center line (CL) of the spherical roller and the axis (O) of the self-aligning roller bearing , when a clearance between the axially outer side surface of the annular member and the inner end surface of the spherical roller is regarded as a clearance Z, the clearances Y and Z have a relation of Y < Z. <EOS>