A method for evaluating an oxide semiconductor film, a method for evaluating a transistor including an oxide semiconductor film, a transistor which includes an oxide semiconductor film and has favorable switching characteristics, and an oxide semiconductor film which is applicable to a transistor and enables the transistor to have favorable switching characteristics are provided. A PL spectrum of an oxide semiconductor film obtained by low-temperature PL spectroscopy has a first curve whose local maximum value is found in a range of 1.6 eV or more and 1.8 eV or less and a second curve whose local maximum value is found in a range of 1.7 eV or more and 2.4 eV or less. A value obtained by dividing the area of the second curve by the sum of the area of the first curve and the area of the second curve is 0.1 or more and less than 1.