Provided are a medicinal agent which is highly safe for use as the treatment of a malignant tumor and is capable of efficiently treating a malignant tumor, that is, a medicinal agent for treating a malignant tumor or for suppressing or preventing the exacerbation thereof, comprising at least one kind of natriuretic peptide receptor GC-A agonist and at least one kind of natriuretic peptide receptor GC-B agonist to be administered in combination a therapeutic method comprising administering the agent etc.
