Abstract: A magnetic sensor device having output characteristics with high precision and a method of manufacturing the same. A thick film resistor is trimmed while a magnetic field is applied to a circuit board at a predetermined angle, thereby adjusting output characteristics of a hybrid integrated circuit on the circuit board and eliminating undesirable misalignment of the mounting position between an MR device and the circuit board. Subsequently, a dowel recess used as a first positioning member formed on the circuit board receives a dowel projection used as a second positioning member formed on a frame, the dowel projection complementary to the dowel recess, thus positioning and assembling the circuit board into the frame. The output characteristics obtained during trimming conform with those after assembly, thus obtaining a magnetic sensor device having output characteristics with high precision and achieving correct detection as a sensor.