The men - all in fancy dress, and part of an organisation called New Fathers 4 Justice - staged the hour-long protest at the Deputy Prime Minister’s office in Nether Green, Sheffield.
They held a banner reading, ‘The family justice system is not in the child’s best interest’.
James Moffat, aged 30, a former chef from Eckington, said his children live in Portsmouth - where he travels to see them for 90 minutes once a fortnight.
He said: “Nick Clegg promised before the election that he would improve access rights but he has done nothing to ensure that happens so far. All we want is a fair deal.”
Trucker Garry Roe, 42, dressed as the Grim Reaper, travelled from Heanor in Derbyshire to take part in the demonstration.
He said: “All I want is for the law to recognise fathers have rights too. We’ve written to our local MPs because we want equal rights, but we’ve been ignored time and again. So now we’re here.”
Roger Crawford, 63, had travelled from Bedford.
“Nick Clegg promised grandparents the right to see their grandchildren,” he said. “But how is he going to achieve that if parents themselves don’t even have equal rights?”
A spokesman for Sheffield Hallam MP Mr Clegg said: “Peaceful, lawful protest is always welcome.
“However the roof of the constituency office, and our next door neighbours’ roof, is private property and their actions could have proven dangerous to themselves and others.”
