PURPOSE: To easily and surely decide an amount of adjustment by preparing a characteristic model and using it.

CONSTITUTION: The respective parts composing the device for automatically adjusting a package 10 are provided with following functions. Namely, a measurement part 1 is provided with a function measuring the output value of an electronic circuit package 4 by a measuring instrument 5. A mechanism part 2 is provided with a function moving a head for adjustment 7 to the position of a trimmer for adjustment 8 by a robot 6 and rotating the trimmer for adjustment 8. A control part 3 gives an input signal to the electronic circuit package 4 by an incorporated controller 9, controls the measurement part 1 and the mechanism part 2 so as to obtain data for preparing a characteristic model, prepares the characteristic model, gives the signal of an input value to be a reference to the electronic circuit package which newly becomes the object of adjustment so as to measure the output value and obtains the rotational amount of the trimmer for adjustment 8 by the characteristic model. Then, in correspondence to the obtained rotational amount of the trimmer for adjustment 8, the control part 3 controls the mechanism part 2 and the head for adjustment 7 so as to rotate the trimmer for adjustment 8 of the electronic circuit package 4.