A mounting state informing apparatus includes a database, an acquisition unit, a first specifying unit, a comparison unit and an output unit. The database stores information upon a mounting position and a direction of each of multiple components belonging to a processing apparatus. The acquisition unit acquires first appearance data, which is obtained by a 3D scanner, indicating a state of an appearance of the processing apparatus. The first specifying unit identifies the multiple components based on the first appearance data and specifies a mounting position and a direction of each of the identified components. The comparison unit compares the specified mounting position and the specified direction of each of the identified components with the information upon the mounting position and the direction stored in the database. The output unit is configured to output a comparison result obtained by the comparison unit.