To provide a paramagnetic metal-containing compound useful as a contrast medium for MRI and a liposome containing the compound.

The polyamide amine dendron lipid containing a paramagnetic metal has a structural formula in which one or more free amino groups in the polyamide amine dendron lipid are bonded through a linker to a paramagnetic metal. The liposome comprises the compound. The contrast medium for MRI comprising the liposome is useful for detecting a tumor site.