A device control system comprising: a wearable device; and an information processing device, the wearable device including a biological sensor that detects biological data of a user, a first communication interface, and a first computer transmitting the biological data detected by the biological sensor by using the first communication interface, the information processing device including a second communication interface, and a second computer receiving the biological data detected by the wearable device by using the second communication interface, estimating user's emotion by arithmetic processing of the received biological data, determining whether or not the user has positive emotion by using a result of the estimation, and in a case where it is determined that the user has positive emotion, transmitting a first control signal to the wearable device by using the second communication interface, characterized by the wearable device further comprising a scent sensor for detecting scent; the first computer receiving the first control signal for storing, in a memory, scent information indicative of a scent component of scent that is estimated to have been smelled by a user who is wearing the wearable device and is obtained by detecting scent around the user who is feeling positive emotion, thereby correspondence between the user's experience involving positive emotion and scent is specified, and transmitting the scent information to the information processing device by using the first communication interface; and the second computer receiving the scent information by using the second communication interface and transmitting, to an environment control device holding a fragrance material, a second control signal for causing the environment control device to eject the fragrance material containing the scent component indicated by the received scent information at a predetermined timing by using the second communication interface. a wearable device; and an information processing device, the wearable device including a biological sensor that detects biological data of a user, a first communication interface, and a first computer transmitting the biological data detected by the biological sensor by using the first communication interface, a biological sensor that detects biological data of a user, a first communication interface, and a first computer transmitting the biological data detected by the biological sensor by using the first communication interface, the information processing device including a second communication interface, and a second computer receiving the biological data detected by the wearable device by using the second communication interface, estimating user's emotion by arithmetic processing of the received biological data, determining whether or not the user has positive emotion by using a result of the estimation, and in a case where it is determined that the user has positive emotion, transmitting a first control signal to the wearable device by using the second communication interface, a second communication interface, and a second computer receiving the biological data detected by the wearable device by using the second communication interface, estimating user's emotion by arithmetic processing of the received biological data, determining whether or not the user has positive emotion by using a result of the estimation, and in a case where it is determined that the user has positive emotion, transmitting a first control signal to the wearable device by using the second communication interface, characterized by the wearable device further comprising a scent sensor for detecting scent; the first computer receiving the first control signal for storing, in a memory, scent information indicative of a scent component of scent that is estimated to have been smelled by a user who is wearing the wearable device and is obtained by detecting scent around the user who is feeling positive emotion, thereby correspondence between the user's experience involving positive emotion and scent is specified, and transmitting the scent information to the information processing device by using the first communication interface; and the second computer receiving the scent information by using the second communication interface and transmitting, to an environment control device holding a fragrance material, a second control signal for causing the environment control device to eject the fragrance material containing the scent component indicated by the received scent information at a predetermined timing by using the second communication interface.