To obtain an imaging unit, a lens barrel, and a portable terminal which can effectively suppress spring-back of solid-state imaging elements, while facilitating height lowering thereof. An imaging unit includes: a solid-state imaging element; and an imaging lens for forming a subject image on a photoelectric conversion part of the solid-state imaging element. An imaging surface of the solid-state imaging element is curved in a manner that a peripheral side is inclined toward an object side relative to a screen center. The imaging lens constrains the solid-state imaging element to prevent a radius of curvature of the imaging surface from varying. Thus, field curvature, distortion aberration, and comatic aberration are appropriately corrected.