A method for treating cancer includes administering to a subject in need of the treatment an anticancer agent composition that includes the following agents as active ingredients; a LAT1 inhibitor, and one or more agents selected from the group consisting of an alkylating agent, a platinum-based antineoplastic agent, an anti-metabolite, a topoisomerase inhibitor, an anti-microtubule polymerizing agent, a hormonal agent, an anti-microtubule depolymerizing agent, an anticancer antibiotic, and a molecular targeted agent.