THE PRESENT INVENTION PROVIDES A TRIAZOLOPYRIDINE COMPOUND HAVING A PROLYL HYDROXYLASE INHIBITORY ACTION AND AN ERYTHROPOIETIN PRODUCTION-INDUCING ABILITY. THE PRESENT INVENTION RELATES TO A COMPOUND REPRESENTED BY THE FOLLOWING FORMULA [I] WHEREIN EACH SYMBOL IS AS DEFINED IN THE SPECIFICATION, OR A PHARMACEUTICALLY ACCEPTABLE SALT THEREOF, OR A SOLVATE THEREOF, AS WELL AS A PROLYL HYDROXYLASE INHIBITOR OR ERYTHROPOIETIN PRODUCTION—INDUCING AGENT CONTAINING THE COMPOUND. THE COMPOUND OF THE PRESENT INVENTION SHOWS A PROLYL HYDROXYLASE INHIBITORY ACTION AND AN ERYTHROPOIETIN PRODUCTION-INDUCING ABILITY AND IS USEFUL AS A PROPHYLACTIC OR THERAPEUTIC AGENT FOR VARIOUS DISEASES AND PATHOLOGIES (DISORDERS) CAUSED BY DECREASED PRODUCTION OF ERYTHROPOIETIN.
