MEASURING INSTRUMENT FOR SEEPAGE LINE

PROBLEM TO BE SOLVED: To easily lower a water level sensor at the tip of a measuring tape down to the surface of water without spoiling a function of measuring a length of the measuring tape nor causing the measuring tape to stick on a wet inner wall surface, etc., when measuring a seepage line of an earth dam, and to make it easy to view graduations of the measuring tape.SOLUTION: A measuring instrument for seepage line includes a measuring tape 3 which has graduations 2 represented and has a flat cross section, a water level sensor 4 which is provided to a tip part of the measuring tape 3, and a notification part 5 which gives notice when the water level sensor 4 comes into contact with the surface of water, and the measuring tape 3 is fitted with sticking prevention parts 8 which swell at the direction orthogonal to the longitudinal direction of the measuring tape 3 at predetermined intervals so as to prevent a measuring hole 54 (measuring pipe 55) from sticking a hole wall.