The Fianna Fáil TD said the number of errors he has made in relation to declarations on his holdings led to the decision.
Deputy Troy said while one mistake was excusable, he had made a number of errors.
He insisted in a statement that he never tried to conceal anything and his biggest mistake was a lack of due diligence.
Robert Troy said he had bought his first property aged twenty and wouldn't apologise for being a landlord - accusing media and opposition of vilifying landlords.
He added he wasn't born with a silver spoon in his mouth and worked for all he had.
Taoiseach Micheál Martin will consider a replacement for Robert Troy in the coming days.
The Taoiseach says Robert Troy has been a very committed, hardworking and efficient Minister of State at the Department of Enterprise, Trade & Employment.
However, Micheál Martin acknowledges Deputy Troy made serious errors in relation to his declarations to the Register of Member’ Interests.
Meanwhile, Tánaiste Leo Varadkar says the Longford-Westmeath TD has left a lasting legacy in the department, 'making a difference to thousands of businesses across the country.'
