To obtain a preventing agent, diagnostic agent or treating agent for lung selective cancer metastasis, also a medicine such as a lung selective cancer metastasis-inhibitor and a proliferation inhibitor for the lung selective cancer metastasis, and further to provide, a method for diagnosing the lung selective cancer metastasis.

The preventing agent or treating agent for the lung selective cancer metastasis containing a substance inhibiting the transmission of information through human VEGF receptor Flt-1 as an active ingredient, the medicines such as the lung selective cancer metastasis-inhibitor and the proliferation inhibitor for the lung selective cancer metastasis containing the substance as an active ingredient, the diagnostic agent of the lung selective cancer metastasis, containing an antibody having a bonding activity toward the human VEGF receptor FLt-1 as an active ingredient, and the method for diagnosing the lung selective cancer metastasis by using the antibody are provided.