PURPOSE: To make a remote communication using a laser beam by providing a means which scans the laser beam in a projection direction and a means which modulates the laser beam with a number corresponding to its scanning angle on both a transmission side and a reception side.

CONSTITUTION: The transmission side sends the ID code of a sender such as an identifier and a number (n) corresponding to the instantaneous value of a scanning angle in order by scanning 1 and the reception side detects the momentary laser beam when the azimuth of the laser beam reaches θ1 and demodulates the ID of the sensor and the (n) to obtain the θ1. Then the reception side makes a scan 2 to send the ID of the sender, a number n1 for the θ1, and a number n' corresponding to the instantaneous value of the scanning angle of the laser beam sent by the reception side in order, and the transmission side detects the momentary laser beam when the azimuth of the laser beam reaches θ2, and then processes it to obtain the θ2. Then the transmission side sends information of the θ2 to the reception side, which obtains the azimuth θ2 of the transmission side. Thus, a line connecting the both is formed and a communication between the both becomes ready.