A pivot head wrench includes a handle, a head, a pivot pin, a linear motion mechanism and a lock mechanism. The pivot pin connects the handle and the head. The linear motion mechanism is disposed at the handle and includes a moving path, wherein the head is disposed in the moving path. The lock mechanism includes a groove and at least one protrusion, wherein one of the groove and the protrusion is disposed at the head while the other is disposed at the linear motion mechanism for engaging with each other, and the protrusion and the groove both are disposed in the moving path.