An electric generator device includes a swinging part, a storage part, a vibration energy generating part, and an electric generator part. The swinging part swings in position due to external swing. The storage part stores a swing power of the swinging part. The vibration energy generating part generates, by the power stored at the storage part, vibration energy having its amplitude and frequency adjusted. The electric generator part converts the vibration energy generated at the vibration energy generating part to electric power. The vibration energy generating part comprises a pendulum to be in contact with a rotary part which is rotated by the power stored at the storage part, thereby to adjust the rotational speed of the rotary part.