PURPOSE: To surely prevent a water proof seal from coming out without enlarging the water proof seal in size.

CONSTITUTION: The insulation barrel section 14 of a female terminal fitting 11 is composed of two seal squeezing pieces 18, and the respective seal squeezing pieces 18 are integrally continued to both the right and left sides in an opened upward shape. The rear end section of each seal squeezing piece 18, that is, the end section in the outside direction of a cavity 23, is bent inward roughly at a right angle so as to be formed into a locking piece section 19. The locking piece section 19 is so designed as to be engaged with the ring shaped end face 21a of a water proof seal 20 when the water proof seal 20 is squeezed so as to be fixed. By this constitution, when the female terminal fitting 11 is to be inserted into the cavity 23, even if the water proof seal 20 is subjected to great insertion resistance, the water proof seal 20 is surely prevented from coming out by the locking piece sections 19.