Abstract: A spanner includes an upper jaw, a handle, a lower jaw, and a resilient member. The upper jaw includes an upper jaw portion, and a pivot portion, and has a front pivot hole and a rear pivot hole both of which extend through the pivot portion. The handle has a connection end extending into the pivot portion and pivoted to the upper jaw at the rear pivot hole. The lower jaw has a lower jaw portion, a tail portion, and an insert part projecting into the pivot portion of the upper jaw. The insert part is pivoted to the upper jaw at the front pivot hole. The resilient member is disposed between the tail portion and the connection end to bias the tail portion away from the connection end so that the lower jaw portion is biased toward the upper jaw portion.