A method for evaluating an efficacy of a chemoradiotherapy against squamous cell carcinoma comprises the following steps (a) to (c): (a) detecting an expression level of at least one gene selected from a SIM2 gene and genes co-expressed with the SIM2 gene in a squamous cell carcinoma specimen isolated from a subject; (b) comparing the expression level detected in the step (a) with a reference expression level of the corresponding gene; and (c) determining that an efficacy of a chemoradiotherapy against squamous cell carcinoma in the subject is high if the expression level in the subject is higher than the reference expression level as a result of the comparison in the step (b).