Provided is a battery pack for electric bicycle and a control method of the battery pack, and the battery pack may prevent the electric bicycle from moving abnormally. The electric bicycle includes a motor and a motion sensor. The battery pack includes a battery, a main switch and a controller. The main switch controls supply of a power which is supplied from the battery to the electric bicycle. The controller outputs a motor hold signal to put the motor in a hold state, when an abnormal motion sensing signal is received from the motion sensor.