An aircraft seat comprising: a base with a relatively movable seat portion (BS1, 112a) and a backrest portion (BS2, 112b); an actuator (ACT) for relatively moving the seat portion (BS1) and the backrest portion (BS2); a biometric sensor (SS) installed on the base and configured to obtain biometric information of a passenger and emit a signal ; a plurality of elastic members (AS) installed on the base; a modification device (PS) configured to change an elastic force of at least one elastic member (AS), and a control device (CONT), characterized in that : the control device (CONT) can determine whether or not the passenger is relaxing and transitioning to a sleep state from the biometric sensor (SS) signal and, in the case that the control device (CONT) determines that the passenger is not relaxed, the control device (CONT) can automatically drive the modification device (PS) in the form of a pump to adjust the internal pressure of a plurality of air cells serving as elastic members (AS) or to provide a slight vibration; or the control device (CONT) can automatically drive the actuator (ACT) to change the seat from a flat state to a chair state as a landing time of the aircraft is approaching in order to wake up and alert the passenger that he or she is about to arrive. a base with a relatively movable seat portion (BS1, 112a) and a backrest portion (BS2, 112b); an actuator (ACT) for relatively moving the seat portion (BS1) and the backrest portion (BS2); a biometric sensor (SS) installed on the base and configured to obtain biometric information of a passenger and emit a signal ; a plurality of elastic members (AS) installed on the base; a modification device (PS) configured to change an elastic force of at least one elastic member (AS), and a control device (CONT), characterized in that : the control device (CONT) can determine whether or not the passenger is relaxing and transitioning to a sleep state from the biometric sensor (SS) signal and, in the case that the control device (CONT) determines that the passenger is not relaxed, the control device (CONT) can automatically drive the modification device (PS) in the form of a pump to adjust the internal pressure of a plurality of air cells serving as elastic members (AS) or to provide a slight vibration; or the control device (CONT) can automatically drive the actuator (ACT) to change the seat from a flat state to a chair state as a landing time of the aircraft is approaching in order to wake up and alert the passenger that he or she is about to arrive. the control device (CONT) can determine whether or not the passenger is relaxing and transitioning to a sleep state from the biometric sensor (SS) signal and, in the case that the control device (CONT) determines that the passenger is not relaxed, the control device (CONT) can automatically drive the modification device (PS) in the form of a pump to adjust the internal pressure of a plurality of air cells serving as elastic members (AS) or to provide a slight vibration; or the control device (CONT) can automatically drive the actuator (ACT) to change the seat from a flat state to a chair state as a landing time of the aircraft is approaching in order to wake up and alert the passenger that he or she is about to arrive. <EOS>