After Thursday's quake, some high-speed trains were halted as a precaution.
Bank of Japan Governor Haruhiko Kuroda, speaking in Washington, said the central bank as working closely with other authorities to avoid any disruption to banking operations. There has been no report of disruption to fund settlement systems so far, he said.
Honda Motor Co suspended output at its motorcycle factory near Kumamoto following the quake, a company spokesman said. Honda planned to inspect production equipment at the factory, which has an annual output capacity of 250,000 units, on Friday to see how soon production can be resumed.
Mitsubishi Electric Corp and tire maker Bridgestone Corp also suspended operations at their factories in the area, Kyodo news agency said.