An optical fiber adapter for optically coupling two optical fiber connectors with each other, the optical fiber adapter comprising: a main body having an accommodation room defined by a first wall, a second wall, a third wall and a fourth wall, the first wall facing the third wall and connecting with the second and fourth walls (515, 514), wherein the accommodation room has opposing first and second openings (528a, 528b) in an axial direction to respectively allow the two optical fiber connectors to insert into the accommodation room to mate with each other; an inner housing positioned within the accommodation room, the inner housing comprising: a flange having a front surface; and a hollow cylinder extending from the front surface of the flange toward the first opening of the accommodation room, the hollow cylinder having an opening facing the first opening of the accommodation room; an elastic shutter member positioned within the accommodation room, the shutter member comprising: a base portion; a shutter plate; and a connecting portion connecting the base portion with the shutter plate; the optical fiber adapter being characterized in that: the optical fiber adapter further comprises a spring positioned within the accommodation room to push the base portion toward the first opening of the accommodation room, wherein the base portion is moved toward the second opening with the insertion of the optical fiber connector into the accommodation room from the first opening, and wherein the shutter plate is pivotally movable about the connecting portion, the base portion is configured to pull the shutter plate to slide on a lateral surface of the hollow cylinder, and the shutter plate is further configured to extend from the connecting portion to a position in front of the opening of the hollow cylinder when no optical fiber connector is inserted into the accommodation room from the first opening. a main body having an accommodation room defined by a first wall, a second wall, a third wall and a fourth wall, the first wall facing the third wall and connecting with the second and fourth walls (515, 514), wherein the accommodation room has opposing first and second openings (528a, 528b) in an axial direction to respectively allow the two optical fiber connectors to insert into the accommodation room to mate with each other; an inner housing positioned within the accommodation room, the inner housing comprising: a flange having a front surface; and a hollow cylinder extending from the front surface of the flange toward the first opening of the accommodation room, the hollow cylinder having an opening facing the first opening of the accommodation room; a flange having a front surface; and a hollow cylinder extending from the front surface of the flange toward the first opening of the accommodation room, the hollow cylinder having an opening facing the first opening of the accommodation room; an elastic shutter member positioned within the accommodation room, the shutter member comprising: a base portion; a shutter plate; and a connecting portion connecting the base portion with the shutter plate; a base portion; a shutter plate; and a connecting portion connecting the base portion with the shutter plate; the optical fiber adapter being characterized in that: the optical fiber adapter further comprises a spring positioned within the accommodation room to push the base portion toward the first opening of the accommodation room, wherein the base portion is moved toward the second opening with the insertion of the optical fiber connector into the accommodation room from the first opening, and wherein the shutter plate is pivotally movable about the connecting portion, the base portion is configured to pull the shutter plate to slide on a lateral surface of the hollow cylinder, and the shutter plate is further configured to extend from the connecting portion to a position in front of the opening of the hollow cylinder when no optical fiber connector is inserted into the accommodation room from the first opening. the optical fiber adapter further comprises a spring positioned within the accommodation room to push the base portion toward the first opening of the accommodation room, wherein the base portion is moved toward the second opening with the insertion of the optical fiber connector into the accommodation room from the first opening, and wherein the shutter plate is pivotally movable about the connecting portion, the base portion is configured to pull the shutter plate to slide on a lateral surface of the hollow cylinder, and the shutter plate is further configured to extend from the connecting portion to a position in front of the opening of the hollow cylinder when no optical fiber connector is inserted into the accommodation room from the first opening.