Provided is a sensor for measuring water levels of groundwater and surface water using magnetostriction displacement and multi measurement system for groundwater and surface water by using the same. The sensor includes an outer case having a hollow space therein and extending in a longitudinal direction, a magnetostriction line spaced apart from an inner wall in the hollow space of the outer case to extend in the longitudinal direction, a floating permanent magnet guided along the magnetostriction line to be movable in the longitudinal direction, the floating permanent magnet being changed in position to correspond to a water level; and a transceiver applying a current pulse into the magnetostriction line to receive an elastic wave that is generated while first magnetic fields formed in a circumferential direction of the magnetostriction line by the current pulse crosses a second magnetic fields formed in an axial direction of the magnetostriction line by the permanent magnet.