An electrical connector adapted to be mated with a mating electrical connector comprises a housing including a cylinder having a receiving passage extending in an axial direction of the electrical connector, a conductive terminal disposed in the receiving passage, and a locking device. The locking device includes a body portion, a locking portion disposed at a first end of the body portion and configured to engage with a mating locking portion of the mating electrical connector to lock the electrical connector with the mating electrical connector, a releasing portion disposed at a second end of the body portion opposite the first end of the body portion and configured to release the engagement between the locking portion and the mating locking portion, and a flexible connecting arm formed in a curved shape and connecting the body portion to an outer surface of the cylinder.