In order to apply magnetostrictive materials in vibration energy harvesting devices, large-sized ingots of Fe–Ga alloy single crystals exhibiting large magnetostriction were successfully grown using the Czochralski method. The performance of power generation using the 〈1 0 0〉-oriented crystal has been evaluated using simply designed devices. Specifically, influences of magnetic fields produced by inverse magnetostriction of the crystal and permanent magnets on power generation have been studied. The results indicated that power generation using the Fe-Ga alloy single crystal result from the inverse magnetostriction and the magnetic fluxes generated by electromagnetic inductions, which are caused by the cyclic relative motion between a coil and permanent magnets using the simple device frame structures. It was shown that the alloy single crystal acts as a magnetic core, and that the alternating current produced via vibration energy harvesting can be converted to direct current for charging batteries.