"Japan's economy faces strong downward pressure, mainly on the production side, due to the effects of the earthquake disaster," the central bank said in a statement.
"Production has declined sharply due to the supply-side constraints caused by the disaster."
The board of the BoJ voted unanimously to keep rates unchanged as it gauges the effects of previous easing measures.
Japan's economy plunged back into recession in January-March, contracting sharply on the impact of the nation's biggest recorded earthquake, a tsunami and a nuclear crisis.
Gross domestic product fell 0.9 percent in the first quarter compared with the previous three months, and marked the second consecutive quarter of contraction, which economists define as a technical recession.
The drop was equivalent to a 3.7 percent fall on an annualised basis.
In the aftermath of the disasters, industrial output saw its biggest ever fall and spending plunged as consumer and business confidence took a tumble.
Many analysts see the downturn worsening in April-June, as nationwide supply.