An electrical connector provided with a housing for retaining a contact and with an electric wire connection mechanism for connecting an electric wire to the contact , the electrical connector having a frontward/rearward direction (D1) in a direction of plug/traction of the electrical connector with respect to a mating object, wherein the housing comprises: a contact accommodating portion for accommodating the contact ; a mechanism accommodating portion for accommodating the electric wire connection mechanism ; a lock arm supported in a cantilever-like manner at a front end portion of the contact accommodation portion in front of the mechanism accommodating portion , the lock arm having a fixed end supported at the front end portion of the contact accommodating portion and a rear end portion as a free end located behind the fixed end , the lock arm being configured for catching the mating object configured to be mated to the electrical connector ; and a protection wall accompanying the lock arm provided on the same side of the housing as the mechanism accommodating portion in an upward/downward direction (D3) of the housing which is perpendicular to the frontward/rearward direction (Dl), wherein the lock arm is provided on an upper side of the contact accommodating portion , and the mechanism accommodating portion is formed with a mechanism front opening located between the rear end portion of the lock arm and the electric wire connection mechanism , characterized in that the rear end portion of the lock arm is formed with an attachment portion to which a releasing operation portion is detachably attached, wherein the releasing operation portion is configured to be pushed for releasing the mating object from the lock arm , wherein the rearward projected area of the lock arm , including the attachment portion , is within the opening region of the mechanism front opening . a contact accommodating portion for accommodating the contact ; a mechanism accommodating portion for accommodating the electric wire connection mechanism ; a lock arm supported in a cantilever-like manner at a front end portion of the contact accommodation portion in front of the mechanism accommodating portion , the lock arm having a fixed end supported at the front end portion of the contact accommodating portion and a rear end portion as a free end located behind the fixed end , the lock arm being configured for catching the mating object configured to be mated to the electrical connector ; and a protection wall accompanying the lock arm provided on the same side of the housing as the mechanism accommodating portion in an upward/downward direction (D3) of the housing which is perpendicular to the frontward/rearward direction (Dl), wherein the lock arm is provided on an upper side of the contact accommodating portion , and the mechanism accommodating portion is formed with a mechanism front opening located between the rear end portion of the lock arm and the electric wire connection mechanism , characterized in that the rear end portion of the lock arm is formed with an attachment portion to which a releasing operation portion is detachably attached, wherein the releasing operation portion is configured to be pushed for releasing the mating object from the lock arm , wherein the rearward projected area of the lock arm , including the attachment portion , is within the opening region of the mechanism front opening . <EOS>