Electrically-driven Mach-Zehnder interferometer type InGaAsP photonic-wire optical switches have been demonstrated using a III-V-on-insulator structure bonded on a thermally oxidized Si with an Al(2)O(3)/InP bonding interfacial layer which enables strong wafer bonding and low propagation loss. Lateral p-i-n junctions in the InGaAsP photonic-wire waveguides were formed by using ion implantation for changing refractive index in the InGaAsP waveguide through carrier injection. Optical switching with 10 dB extinction ratio was achieved with driving current of 200 µA which is approximately 10 times smaller than that of Si photonic-wire optical switch owing to larger free-carrier effect in InGaAsP than that in Si.