A wristband-type information processing device (1, 1-1) comprising: a band section configured to be worn on a wrist of a user; a sensor unit configured to detect a motion and a state of the user; a control unit configured to determine whether or not the motion detected by the sensor unit is a tapping input of the user to the wristband-type information processing device (1, 1-1) and to generate, when the motion is determined to be the tapping input, a first vibration signal to be transmitted to another associated wristband-type information processing device (1, 1-2); and to determine whether or not the state detected by the sensor unit is a predetermined state and to generate, when the state is determined to be the predetermined state, a first state signal for notifying another user wearing the other associated wristband-type information processing device (1, 1-2) of the state of the user detected by the sensor unit; a communication unit configured to transmit, when the motion is determined to be the tapping input, the first vibration signal to the other wristband-type information processing device (1, 1-2), to transmit, when the state is determined to be the predetermined state, the first state signal to the other wristband-type information processing device (1, 1-2), and to receive a second vibration signal generated according to another tapping input of the other user from the other wristband-type information processing device (1, 1-2); and a notifying unit, wherein, when the communication unit of the wristband-type information processing device (1, 1-1) receives the second vibration signal from the other wristband-type information processing device (1, 1-2) together with information indicating that the other tapping input according to which the second vibration signal was generated, was performed using the first state signal as a trigger after the communication unit of the wristband-type information processing device (1, 1-1) had transmitted the first state signal to the other wristband-type information processing device (1, 1-2), the notifying unit of the wristband-type information processing device (1, 1-1) is configured to notify the user of the wristband-type information processing device (1, 1-1) of information indicating the fact that the second vibration signal has been transmitted from the other wristband-type terminal (1, 1-2) using the first state signal as the trigger. a band section configured to be worn on a wrist of a user; a sensor unit configured to detect a motion and a state of the user; a control unit configured to determine whether or not the motion detected by the sensor unit is a tapping input of the user to the wristband-type information processing device (1, 1-1) and to generate, when the motion is determined to be the tapping input, a first vibration signal to be transmitted to another associated wristband-type information processing device (1, 1-2); and to determine whether or not the state detected by the sensor unit is a predetermined state and to generate, when the state is determined to be the predetermined state, a first state signal for notifying another user wearing the other associated wristband-type information processing device (1, 1-2) of the state of the user detected by the sensor unit; to determine whether or not the motion detected by the sensor unit is a tapping input of the user to the wristband-type information processing device (1, 1-1) and to generate, when the motion is determined to be the tapping input, a first vibration signal to be transmitted to another associated wristband-type information processing device (1, 1-2); and to determine whether or not the state detected by the sensor unit is a predetermined state and to generate, when the state is determined to be the predetermined state, a first state signal for notifying another user wearing the other associated wristband-type information processing device (1, 1-2) of the state of the user detected by the sensor unit; a communication unit configured to transmit, when the motion is determined to be the tapping input, the first vibration signal to the other wristband-type information processing device (1, 1-2), to transmit, when the state is determined to be the predetermined state, the first state signal to the other wristband-type information processing device (1, 1-2), and to receive a second vibration signal generated according to another tapping input of the other user from the other wristband-type information processing device (1, 1-2); and a notifying unit, wherein, when the communication unit of the wristband-type information processing device (1, 1-1) receives the second vibration signal from the other wristband-type information processing device (1, 1-2) together with information indicating that the other tapping input according to which the second vibration signal was generated, was performed using the first state signal as a trigger after the communication unit of the wristband-type information processing device (1, 1-1) had transmitted the first state signal to the other wristband-type information processing device (1, 1-2), the notifying unit of the wristband-type information processing device (1, 1-1) is configured to notify the user of the wristband-type information processing device (1, 1-1) of information indicating the fact that the second vibration signal has been transmitted from the other wristband-type terminal (1, 1-2) using the first state signal as the trigger.