The Queensland Government has denied it is throwing away up to $300,000 by joining a High Court challenge to the mining tax.

The Liberal National Party government this week confirmed it will join the Fortescue Metals Group's court challenge to the Federal Government's minerals resource rent tax.

Queensland Attorney-General Jarrod Bleijie, who said the action will cost up to $300,000, on Tuesday denied it was a waste of money.

That is despite polls pointing to a federal election win for the coalition, which has vowed to repeal the tax.

"Although I'd love to see that assumption (of a coalition win) come true, that's an assumption no one in politics ever makes," Mr Bleijie told ABC Radio.

He said the Queensland Government had an obligation to make its opposition to the tax known by joining the Fortescue challenge.

"We've got to do whatever we can to make sure we're sticking up for Queensland jobs and industry," Mr Bleijie said.