A gyroscopic power generator that generates a power of 1.8 W is developed with a rotor of 100 mm diameter and 500 rpm spin speed. In conventional vibration generators, which use simple vibrations of an inner pendulum, the output power has been less than 60 mW. Gyroscopic generators increase the inertial force by rotating the pendulum at a high speed and generate about 50 times greater power than the conventional ones. However, wearable gyro generators that operate under arbitrary vibrations have not been realized because the gyro torque and the electromechanical transformation efficiency are greatly reduced by miniaturization. In this study, first, a theoretical model is developed to clarify the basic characteristics of the generator. Next, a desktop-sized generator that works under any vibration is developed using highly precise motors and gears determined by the theory; the optimum rotor, motor, and gear parameters are decided according to the approximate solution of the mathematical model. Next, mechanical and electrical characteristics are measured to show the validity of the theory. Finally, a wearable test device is produced by modifying a 2.52" hard disk drive (HDD) to show the possibility of obtaining a practical generator.