To eliminate finishing stakes and accumulation of errors subsequent to measurements in a structure foundation work and shorten a construction period.

A first and a second measurement point 21, 22 are set at a construction foundation member 10. A first and a second reference point 31, 32 are set at a site of the foundation work, and a first and a second survey means 41, 42 are arranged respectively at the points. A height difference hx of the reference points is operated by a reference point height difference operation means 51 from data obtained by measuring the second reference point 32 by the first survey means 41. The construction foundation member 10 is placed at a predetermined position. The first measurement point 21 is measured by the first survey means 41, and a first height ha is operated by a first height operation means 61. On the other hand, a second height hb is operated by a second height operation means 62 from data obtained by measuring the second measurement point 22 by the second survey means 42 and the height different hx. A measurement point height difference (d) is operated by a measurement point height difference operation means 71 from the heights ha and hb. The height difference (d) is output by a data output means 72.