A coil device includes a coil portion, an element body, and a terminal electrode. The coil portion is formed by a wire wound in a coil shape. The element body contains the coil portion where a part of an outer circumference of a lead-out part of the coil portion is exposed as an exposed portion from a bottom surface of the element body and where the rest of the outer circumference of the lead-out part of the coil portion is embedded as an embedded portion in the element body. The terminal electrode is formed on the bottom surface of the element body and connected with the exposed portion. An embedded length of the outer circumference of the lead-out part in the embedded portion is larger than a substantially half of a full length of the outer circumference of the lead-out part.