Police arrested the owner of a construction firm Thursday on suspicion of placing a bomb at a police station in Furukawa, Miyagi Prefecture.
Investigators believe Fumio Ando, 59, also set off two bombs in the area this month.
Ando was arrested for allegedly placing the bomb outside the main entrance of the police station on Oct. 14. The bomb was made from two sticks of dynamite attached to a timer and hidden in a plastic bag.
The police found the bomb after a visitor told them he had seen a man placing the bag in shrubs at the entrance. They later detonated the device.
On Oct. 8, an explosion occurred at a pachinko parlor, while Oct. 9 saw another blast at an unmanned consumer finance office.
Both places are within 1 km of the police station.
Ando reportedly admitted his involvement in these cases, according to the police.