An optical connector comprising: an optical fiber; a ferrule which is provided at an end of the optical fiber and through which a core of the optical fiber is to be inserted; a housing in which the ferrule is accommodated; a holder, provided with a ferrule retainer, which is inserted into the housing and engaged with the housing through an engagement portion, the ferrule retainer allowing the housing to hold the ferrule; a pair of ribs integrally connected to each other through the ferrule retainer, which are provided in the holder so as to extend along an inserting direction of the holder into the housing, the ferrule retainer provided between the pair of ribs; and a pair of fitting portions which are groove portions and are provided in the housing and to which the ribs are to be fitted to suppress a positional displacement where the holder may be pivoted or inclined to the housing when assembling the holder to the housing, the pair of ribs fitted to the pair of fitting portions when inserting the holder into the housing, wherein the engagement portion includes: a temporary engagement portion configured to allow the holder to be held in the housing in a temporary engagement position and allow the ferrule to be accommodated in the housing; and a formal engagement portion configured to allow the holder to be inserted into the housing under a condition that the ferrule is accommodated in the housing and allow the holder to be held in the housing in a formal engagement position; wherein the pair of ribs are configured to mate with the fitting portions in the temporary engagement position. an optical fiber; a ferrule which is provided at an end of the optical fiber and through which a core of the optical fiber is to be inserted; a housing in which the ferrule is accommodated; a holder, provided with a ferrule retainer, which is inserted into the housing and engaged with the housing through an engagement portion, the ferrule retainer allowing the housing to hold the ferrule; a pair of ribs integrally connected to each other through the ferrule retainer, which are provided in the holder so as to extend along an inserting direction of the holder into the housing, the ferrule retainer provided between the pair of ribs; and a pair of fitting portions which are groove portions and are provided in the housing and to which the ribs are to be fitted to suppress a positional displacement where the holder may be pivoted or inclined to the housing when assembling the holder to the housing, the pair of ribs fitted to the pair of fitting portions when inserting the holder into the housing, the engagement portion includes: a temporary engagement portion configured to allow the holder to be held in the housing in a temporary engagement position and allow the ferrule to be accommodated in the housing; and a formal engagement portion configured to allow the holder to be inserted into the housing under a condition that the ferrule is accommodated in the housing and allow the holder to be held in the housing in a formal engagement position; a temporary engagement portion configured to allow the holder to be held in the housing in a temporary engagement position and allow the ferrule to be accommodated in the housing; and a formal engagement portion configured to allow the holder to be inserted into the housing under a condition that the ferrule is accommodated in the housing and allow the holder to be held in the housing in a formal engagement position; wherein the pair of ribs are configured to mate with the fitting portions in the temporary engagement position.