Disclosed is an imaging lens by which astigmatism and field curvature are satisfactorily corrected by arranging on a first surface a concave surface having an appropriate radius of curvature. Condition (1) defines the radius of curvature of the concave surface arranged on the object-side surface of a bonded compound lens. By fulfilling condition (1), a lens can be obtained in which astigmatism and field curvature are satisfactorily corrected. Condition (1): −1.5