Provided are an air up type transistor which has high electrical connection reliability and high productivity, and is capable of exhibiting good transistor characteristics while achieving microfabrication, and a manufacturing method of a transistor. A semiconductor layer is formed on an upper surface of a support precursor layer which becomes a semiconductor layer support and then a part of the semiconductor layer is removed to form one or more opening portions from which the support precursor layer is exposed. Two etching protective layers are formed on the semiconductor layer such that the two etching protective layers are separated from each other and at least a part of the opening portion is positioned in a region between the two etching protective layers. A part of the support precursor layer is removed by bringing an etchant into contact with the support precursor layer through the plurality of opening portions, thereby forming a space at a position corresponding to a region between the two etching protective layers so as to form two semiconductor layer supports that are arranged with the space interposed therebetween.