He was speaking as gardaí decided not to move forward with an investigation into comments made by British actor Stephen Fry in an interview with Gay Byrne on RTÉ in February 2015.
“It’s silly. It’s a bit embarrassing. It needs to be changed,” said Mr Harris.
“I’m very pleased that the Government wishes to see a referendum in relation to this issue. It obviously does require constitutional change.”
Gardaí said they spoke to the person who made the original complaint but have failed to find sufficient numbers of people outraged by Fry’s comments.
A spokesperson for Justice Minister Frances Fitzgerald said a decision on the scheduling of a referendum on blasphemy would be made in the light of the Government’s legislative programme.
Mr Harris said he hoped a referendum would be held sooner rather than later.
“This is a democracy,” he said. “People have the right to express whatever view they do.
“Stephen Fry, regardless of your own religious views, was clearly making a number of points that he clearly felt very strongly about in his usual witty way. I think we do need a referendum.”
Mr Harris’s comments were echoed by former justice minister Dermot Ahern, who said he would have deleted the blasphemy provision from the Constitution if he could, but he was not prepared to hold a referendum on the issue in 2009, the year in which a specific offence of blasphemy was introduced under the Defamation Act.
“If a referendum had been called it would have brought every headbanger in the country, on both sides, into the debate,” said Mr Ahern.
A number of lay groups, including atheists, have called for a repeal of the current law, saying it makes the case harder to argue against similar laws elsewhere.
Michael Nugent, chair of Atheist Ireland, has described as a “betrayal” the Government’s failure to hold a referendum on the matter.
The Organisation of Islamic Co-operation — which has 57 member states — cites Ireland’s law as best practice and has proposed the adoption of the precise wording in the Irish Constitution prohibiting blasphemy.
That organisation is led by Pakistan, where a Christian woman, Asia Bibi, is awaiting execution for allegedly insulting the Prophet Mohammed after drinking water from the same fountain as Muslim neighbours.
However, the leader of Muslims in Ireland has said Ireland’s blasphemy laws protect against “a charged atmosphere” in Ireland, in a world threatened by terror.
Trinity lecturer Ali Selim said removing the legislation would be “unhealthy and not helpful” and described as “irrational” those calling for a referendum.
“The law of blasphemy helps secure a positive co-existence,” said Dr Selim. “It is not just to protect those in the Muslim community, it is to protect those of all faith and, indeed, those of no faith.
“It has to be there to regulate freedom of expression. We are very pro free expression, responsible free expression. But if it is not regulated it will turn into aggression — and it will invite aggression.”