With none of the nation's viable nuclear reactors in operation, the target indicates an intention to bring most, if not all of them, back online.
Japan's intended energy mix - what proportion of power comes from which sources - has been a subject of hot debate for months, not least because without it, Tokyo has been unable to make international commitments to reduce greenhouse gas emissions.
In its proposal, which will be debated by the government for final policy formulation by the end of next month, the industry ministry said by 2030, about 20-22 per cent of the country's electricity should come from nuclear power.
The industry ministry favours nuclear power as a way to cut emission of carbon dioxide and other greenhouse gases, despite a groundswell of public opposition since the nuclear crisis in Fukushima.
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Reactors at the Fukushima Dai-ichi plant went into meltdown in March 2011 after a tsunami swamped their cooling systems - setting off the worst atomic disaster since Chernobyl in 1986.
Japan's entire stable of nuclear power stations was gradually switched off following the disaster, while tens of thousands of people were evacuated due to concerns about radiation exposure.
Pro-nuclear premier Shinzo Abe and the country's business sector have however since pushed to restart plants that once supplied more than one quarter of Japan's electricity, as a plunging yen had sent energy import bills through the roof.
Abe's government has pledged to lower the country's dependence on nuclear power and promote so-called "green energy", but insists that heavy reliance on renewables is unrealistic because of cost and stability issues.
Japan's pro-nuclear lobby said last week that 2015 would be the year reactors are restarted, despite public wariness.
But the 20-22 per cent supply figure indicates that most, if not all, of the remaining 43 reactors will have to be restarted, though most have yet to receive the green light from regulators.