The optical transmission module 1 includes an optical fiber 20 having a circular cross section and an end surface having an inclined surface 20SA, and an optical element unit 60 including the optical element 10, and is arranged on the outer periphery of the end of the optical fiber 20 in the optical axis direction. There is a notch surface 20SA extending, and the angle of the inclined surface 20SA with respect to the main surface 10SA of the optical element 10 by the notch surface 20SA is defined as an angle at which the light guided through the optical fiber 20 is optically coupled to the optical element 10. ing.光伝送モジュール１は、断面が円形で端面が傾斜面２０ＳＡの光ファイバ２０と、光素子１０を含む光素子部６０と、を具備し、光ファイバ２０の端部の外周に、光軸方向に延在する切り欠き面２０ＳＡがあり、切り欠き面２０ＳＡにより傾斜面２０ＳＡの光素子１０の主面１０ＳＡに対する角度が光ファイバ２０を導光される光が光素子１０と光結合する角度に規定されている。
