A physiological information system includes: a plurality of physiological information sensors configured to acquire physiological information data of a subject being tested, and a physiological information processing apparatus communicatively connected to each of the plurality of physiological information sensors. The physiological information processing apparatus is configured to transmit a synchronous packet toward each of the plurality of physiological information sensors. Each of the plurality of physiological information sensors is configured to: acquire the physiological information data of the subject being tested; receive the synchronous packet transmitted from the physiological information processing apparatus or a trigger signal associated with the synchronous packet; start AD conversion processing for the acquired physiological information data when receiving the synchronous packet or the trigger signal; and transmit the physiological information data converted into digital data to the physiological information processing apparatus.