Abstract: The present invention relates to a method for predicting the postoperative prognosis of a lung adenocarcinoma patient with high sensitivity and/or specificity by identifying a protein with an expression level that specifically varies in a lung adenocarcinoma patient, comprising: step (a) of determining expression levels of myosin IIA and/or vimentin in a biological sample collected from a lung adenocarcinoma patient; and step (b) of predicting or determining a prognosis based on the expression levels of myosin IIA and/or vimentin obtained as a result of determination.