Provided is a shape measurement system which is installed in a work machine and which includes: a target detection unit that detects a target constructed by the work machine and that outputs information regarding the target; an arithmetic unit that obtains and outputs shape information representing the three-dimensional shape of the target by using the information regarding the target detected by the target detection unit; and a changing unit that changes a measurement condition used when the arithmetic unit obtains the shape information. The measurement condition is within a range of the target information used when the arithmetic unit obtains the shape information.