A rotation transmission device comprising: a tubular housing having two open ends; an input shaft having one end thereof received in the housing ; an output shaft arranged coaxially with the input shaft , and having one end of the output shaft received in the housing ; an inner ring provided at a portion of the input shaft received in the housing ; an outer ring provided at a portion of the output shaft received in the housing , and surrounding the inner ring ; engaging elements (5a and 5b) mounted between an inner periphery of the outer ring and an outer periphery of the inner ring ; an engaging element retainer supported so as to be movable between an engaged position where the engaging elements (5a and 5b) are engaged between the outer ring and the inner ring by the engaging element retainer , and a disengaged position where the engaging elements (5a and 5b) are disengaged from the outer ring and the inner ring by the engaging element retainer ; a driving source for moving the engaging element retainer , the driving source comprising an electromagnet mounted at an end portion of the housing on a side of the input shaft ; a first bearing mounted between the electromagnet and the input shaft ; a second bearing mounted between an end portion of the housing on a side of the output shaft and the output shaft ; and a third bearing mounted between the inner ring and the outer ring , wherein the rotation transmission device further comprises a fourth bearing arranged in such a manner as to prevent inclination of axes of the input shaft and the output shaft relative to each other, characterized in that the fourth bearing is provided between the inner ring and the outer ring , in juxtaposition with the third bearing . a tubular housing having two open ends; an input shaft having one end thereof received in the housing ; an output shaft arranged coaxially with the input shaft , and having one end of the output shaft received in the housing ; an inner ring provided at a portion of the input shaft received in the housing ; an outer ring provided at a portion of the output shaft received in the housing , and surrounding the inner ring ; engaging elements (5a and 5b) mounted between an inner periphery of the outer ring and an outer periphery of the inner ring ; an engaging element retainer supported so as to be movable between an engaged position where the engaging elements (5a and 5b) are engaged between the outer ring and the inner ring by the engaging element retainer , and a disengaged position where the engaging elements (5a and 5b) are disengaged from the outer ring and the inner ring by the engaging element retainer ; a driving source for moving the engaging element retainer , the driving source comprising an electromagnet mounted at an end portion of the housing on a side of the input shaft ; a first bearing mounted between the electromagnet and the input shaft ; a second bearing mounted between an end portion of the housing on a side of the output shaft and the output shaft ; and a third bearing mounted between the inner ring and the outer ring , wherein the rotation transmission device further comprises a fourth bearing arranged in such a manner as to prevent inclination of axes of the input shaft and the output shaft relative to each other, characterized in that the fourth bearing is provided between the inner ring and the outer ring , in juxtaposition with the third bearing . <EOS>