An imidazoline derivative represented by general formula (1), wherein R1 represents a water- or fat-soluble substituent, in particular, carboxyl or carbomethoxy, or a pharmaceutically acceptable salt group thereof. A process for producing the same. A blood pressure retentive containing as the active ingredient the above imidazoline derivative or another imidazoline derivative wherein R1 in formula (1) represents hydrogen. The above imidazoline derivative is a novel substance, and both this compound and the imidazoline derivative wherein R1 represents hydrogen are useful as the blood pressure retentive for treating hypotensive shock by removing excessive NO which is the substantial ingredient of a vascular smooth muscle relaxant (EDRF).