To enable detection of probability that a program of normal control means is rewritten and modified in a measurement system.

Detection of probability that the normal control means is modified to a control means the program of which is rewritten is enabled by providing the measurement system with a measurement means 101 that measures use quantity, a transmitting means 102 that transmits measurement data by the measurement means 101, a control means 103 that controls the measurement means and the transmitting means, a casing 104 in which the system is stored and an open/close detection means 105 that observe open/close states of the casing and monitoring open/close of the casing 104 by the open/close detection means 105.