To provide a temporary structure soundness determination system for determining on the soundness of a temporary structure which is a measured object by using a GPS.

This temporary structure soundness determination system 1 includes a GPS receiver 15 placed on a temporary scaffold 11 for construction and a computer 16 for calculating baseline vectors 17A to 17E between GPS antennas 13A to 13D based on observation data received from a GPS satellite 12 by a receiver set 14 of the GPS receiver 15. The computer 16 measures residual deformation of the temporary scaffold 11 by using points of difference in compared elements between a reference triangle 22 depicted by using the baseline vectors 17A to 17E and a measured triangle 23.