An organic material having at least one aromatic conjugated π-electron system is selected. The purity of the organic material is improved by purification, and a conduction mechanism of the organic material is confirmed by a time-of-flight method, whereby a liquid phase of the organic material is usable as an organic semiconductor. A method that enables the usage of a liquid phase of an organic material as an organic semiconductor is provided. The method involves confirming the electronic conduction of the organic material having at least one aromatic conjugated π-electron system by evaluation of a charge transport property using a time-of-flight method, and by evaluation of a dilution effect caused by addition of a diluent.