A magnetic head positioning mechanism is provided which is excellent in shock-resistance and can achieve high positioning accuracy. By constructing the magnetic head positioning mechanism so that a fine actuator section is composed of an actuator spring made from a thin steel plate, a base plate made from a thick steel plate to be junctioned to the actuator spring, stiffness of the fine actuator section in a vertical direction can be improved with flexibility of a driving spring section mounted on the actuator spring being still kept, that is, with sufficient positioning accuracy and satisfactory stroke being maintained. Moreover, by designing a strength of the fine actuator section so that the actuator spring and a holder arm do not overlap when the base plate is connected to the holder arm, the fine actuator section can be made thin and implementing of the fine actuator section among narrow plates in a positioning device is made easy.