A calcaneal bisector for indicating a calcaneal bisection line of a heel firstly includes a frame and a first plate mounted relative to the frame. One side of the heel can be aligned to the first plate when the bisector is in use. The bisector also includes a second plate movably mounted to the frame, and the second plate is slidable relative to the first plate for aligning to the other side of the heel. The bisector further includes an indicator movably mounted relative to the frame for indicating the calcaneal bisection line and a transmission mechanism disposed between the plates and the indicator for correlating movements of the indicator and the relative movements of the plates so as to ascertain the calcaneal bisection line.