A state detection device (1) stores first information obtained from an environment sensor and second information obtained from a motion sensor in a predetermined segment in a data recording DB (21). The state detection device (1) specifies a behavior segment indicating a segment in which a subject performs a specific behavior and a non-behavior segment indicating a segment in which the subject does not perform the specific behavior using the second information stored in the data recording DB (21). The state detection device (1) determines a feature amount to be used for detecting a specific state of the subject using respective values of a plurality of feature amounts included in the first information stored in the data recording DB (21) in each of the behavior segment and the non-behavior segment and determines a threshold value for the determined feature amount, for distinguishing a behavior and a non-behavior. The state detection device (1) is configured to detect the specific state of the subject from the information obtained from the environment sensor using the determined feature amount and the determined threshold value. In this way, it is possible to detect the behavior of the subject depending on the situation of the subject when detecting the subject's behavior.
