A method for predicting an effectiveness of chemotherapy is described. The method comprises a comparing step and a predicting step. The comparing step is a step of comparing a threshold value with a parameter of a cyclin dependent kinase (CDK) included in a sample containing a tumor cell obtained from a human patient. The predicting step is a step of predicting the effectiveness based on a comparison result of said comparing step. Above stated parameter is selected from the group consisting of an activity, an expression level, and a ratio of activity to expression level.