The present disclosure relates to a magnetic resonance imaging (MRI) contrast agent containing a gadolinium complex, and more specically, to a DO3A-tranexamic acid compound having a structure of a chemical formula 1, or an ester compound thereof, and gadolinium complexes thereof. The DO3A-tranexamic acid compound or the ester compound thereof may be used to prepare gadolinium complexes. The gadolinium complexes exhibit thermodynamic and kinetic stabilities, and show the relaxation rate equal to that of the clinical contrast agent which is currently commercially available. Therefore, the gadolinium complexes can be widely used as an MRI contrast agent.