Arwel Rees Thomas, 51, of Llanfachreth near Dolgellau, win Wales, was cutting up another tree when the accident happened.
He suffered a serious head injury, the coroner said.
The hearing at Caernarfon heard he was using a chainsaw to clear storm-damaged trees from a relative’s house near Dolgellau in April 2014.North Wales deputy coroner Nicola Jones said: "This was a very unusual incident which fortunately we don’t see very often. He was properly dressed and equipped and was very experienced in forestry work. I am satisfied there were no other contributory factors. In the circumstances we may never know how the tree fell onto him but the obvious conclusion is that death was due to an accident."