The "terrorist explosion" struck in the Shiite village of Dair outside the capital Manama late yesterday and wounded "two on-duty policemen assigned to secure the road," including the one who later died, the ministry said on Twitter.
It gave no further details.
It was the second reported blast during the protests marking the third anniversary of the uprising among the Gulf state's Shiite majority for a constitutional monarchy in the Sunni-ruled kingdom.
The blasts struck as protesters took to the streets in several areas of the small but strategic Gulf archipelago, which is home base to the US Fifth Fleet.
Shiite villages have been at the forefront of the campaign among the majority community for the ruling Khalifa family to surrender its grip on all key cabinet posts in favour of an elected government.