A female terminal fitting (F) includes a rectangular tubular main body (10). The main body (10) has a rear base plate (14). Left and right side plates (15) are connected at substantially right angles to opposite left and right sides of the rear base plate (14). A main spring piece (20) is accommodated in the main body (10) and is configured to resiliently contact a tab (T) of a mating terminal (M) inserted into the main body (10). An auxiliary spring piece (23) is cantilevered from the rear base plate (14), is accommodated in the main body (10) and is configured to apply a resilient pressing force toward the tab (T) to the main spring piece (20). A reinforcing portion (28) is formed by striking a range from a base end part (23R) of the auxiliary spring piece 23 to the rear base plate (14).