A method for manufacturing an oscillation type electromagnetic power generator including a power generation coil in which two or more solenoid coils are connected in series, and a movable magnet including a plurality of magnets (45, 46) which are arranged such that magnetic poles of magnets (45, 46) facing each other have the same polarity, the movable magnet located inside of the power generation coil and movable in a direction along a winding axis of the power generation coil, wherein the two or more solenoid coils of the power generation coil are spaced apart one from another with a predetermined coil gap and wound in directions reverse to each other for every adjacent coils, adjacent magnets (45, 46) of the movable magnet are connected to each other via a spacer having a predetermined thickness in such a manner that the poles with the same polarity are opposed to each other, a coil pitch which is a total dimension of a coil length of one solenoid coil of the two or more solenoid coils and the coil gap is equal to a magnet pitch which is a total dimension of a magnet length of one magnet (45, 46) of the movable magnet and the thickness of the spacer, and the coil length is shorter than the magnet length, characterized in that the method comprises the steps of: making a solenoid coil having a predetermined coil diameter, a predetermined number of turns per unit length, and a coil length which is at least three times longer than the coil diameter; measuring rise characteristics of an output voltage when allowing a magnet (45,46) having a predetermined magnet diameter and a length that is the same as the coil length to pass through the solenoid coil at a predetermined passage speed; obtaining from the measured rise characteristics a rise time elapsing from when the output voltage reaches 10% of a peak amplitude to when the output voltage reaches 90% of the peak amplitude; and determining a length which is two times as long as a length obtained from the rise time and the passage speed as a length of the magnet pitch; wherein, after obtaining the magnet pitch, dimensional conditions of the coil gap and the spacer for the movable magnet are determined under the conditions that the total dimension of the coil length of the solenoid coil and the coil gap is set to be equal to the magnet pitch; and the magnet length is longer than the coil length of the solenoid coil. making a solenoid coil having a predetermined coil diameter, a predetermined number of turns per unit length, and a coil length which is at least three times longer than the coil diameter; measuring rise characteristics of an output voltage when allowing a magnet (45,46) having a predetermined magnet diameter and a length that is the same as the coil length to pass through the solenoid coil at a predetermined passage speed; obtaining from the measured rise characteristics a rise time elapsing from when the output voltage reaches 10% of a peak amplitude to when the output voltage reaches 90% of the peak amplitude; and determining a length which is two times as long as a length obtained from the rise time and the passage speed as a length of the magnet pitch; wherein, after obtaining the magnet pitch, dimensional conditions of the coil gap and the spacer for the movable magnet are determined under the conditions that the total dimension of the coil length of the solenoid coil and the coil gap is set to be equal to the magnet pitch; and the magnet length is longer than the coil length of the solenoid coil.