Authentication between a data communication device and a mobile terminal can be readily achieved such that data obtained by the data communication device can be transmitted to the mobile terminal.A management server (50a to 50d) includes a user management database (60) in which mobile terminal identification information on the mobile terminal (40a, 40b) and working machine identification information on a sold working machine are registered to be related to each other, a user registration determination unit (53) adapted to determine whether or not the mobile terminal (40a, 40b) and the working machine are registered to be related to each other on the basis of the mobile terminal identification information and the working machine identification information outputted from the mobile terminal (40a, 40b) and the mobile terminal identification information and the working machine identification information stored in the user management database (60), and an authorization information output unit (54) adapted to output an authorization key necessary for wireless communication between the mobile terminal (40a, 40b) and the working machine in a case where the user registration determination unit (53) determines that the mobile terminal (40a, 40b) and the working machine are registered to be related to each other.
