The invention relates to the technical field of headphones, and provides a headphone main body and an in-ear headphone. When two of the headphone main bodies are worn in left and right ear cavities separately, a rotating member drives a connecting end part of a headphone line to rotate toward the side part of a headphone shell along with the dead weight of the rotating member and a downward pulling force applied to the rotating member by the headphone line, so that the headphone lines sag naturally without making the left and right ear cavities unconformable; and when the two headphone main bodies are taken off, the two headphone main bodies are naturally suspended in front of the chest or behind the back of a user, the rotating members in the headphone main bodies drive the connecting ends of the headphone lines to turn over toward the upper ends of the headphone shells under the action of the dead weight of the headphone main bodies, thus the headphone lines are in a natural downward extending state, and each headphone line and a control rod are positioned in a straight line, thereby greatly reducing partial wear degree of the headphone lines at lead-out hole ports of second lead hole holes, and prolonging the service life of the headphone lines, namely, prolonging the service life of the headphone main bodies and the headphone lines.