Mr Hutton has issued the following statement:
"I have decided to resign from the Government. I will also be standing down as a Member of Parliament at the next general election.
"This is not the place to go into my reasons for leaving. But I can say that it has been one of the hardest decisions I have ever had to take. I was delighted to be appointed Secretary of State for Defence last October. I have always had the deepest admiration for our Armed Forces, and everything they do.
"My respect and affection for our Service personnel, and the civilians who support them, has grown still further since I became Defence Secretary. Seeing our people go about their tasks at home and on operations with the professionalism and commitment for which they are renowned has impressed me immensely. It has been my privilege to have been responsible for the best armed forces in the world.
"My decision has been made even harder by the fact that our forces are engaged in very difficult operations in Afghanistan, having completed successfully our combat mission in Iraq. I am humbled by the sacrifice of our young men and women.
"I will be very sad to leave the Ministry of Defence. I wish all of you - and your families - well for the future and thank every one of you for your efforts."