Provided are an iminopyridine derivative having a selective α1D adrenergic receptor antagonistic action and useful as an agent for the prophylaxis or treatment of a lower urinary tract disease and the like, and a screening method for a compound having an α1D adrenergic receptor antagonistic action. An α1D adrenergic receptor antagonist containing a compound represented by the formula:wherein each symbol is as defined in the specification, or a salt thereof, and a method of screening for an agent having an α1D adrenergic receptor antagonistic action for the prophylaxis or treatment of a lower urinary tract disease, which includes measuring the bladder smooth muscle tension of rats with bladder outlet obstruction.
