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 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 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 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.