To provide a therapeutic agent for metastatic cancer and a cancer metastasis inhibitor which are highly safe and efficaciously treat metastatic cancer and inhibit cancer metastasis, and especially efficaciously treat and inhibit cancer metastasis to bone and liver. There are provided a therapeutic agent for metastatic cancer and a cancer metastasis inhibitor each of which includes a platinum complex having an anticancer activity as an active ingredient. The platinum complex is preferably cisplatin. The therapeutic agent for metastatic cancer is advantageously usable for treating metastatic cancer to bone and/or liver. The cancer metastasis inhibitor is advantageously usable as a cancer metastasis inhibitor for inhibiting metastasis to bone and/or liver. These agents can advantageously further include a bisphosphonate as another active ingredient.