The present invention provides a novel 2-pyridyl substituted imidazole derivative, or a pharmaceutically acceptable salt or solvate thereof, which selectively inhibits the transforming growth factor-β (TGF-β) type I receptor (ALK5) and/or the activin type I receptor (ALK4); a pharmaceutical composition comprising same as an active ingredient; and a use of the 2-pyridyl substituted imidazole derivative for the manufacture of a medicament for preventing or treating a disease mediated by ALK5 and/or ALK4 receptors in a mammal.