A head-mounted display comprising: a main body in which a display is built; a wearing band extending from the main body to a rear side and having a shape enclosing a head of a user as a whole; a right-side extending section configured to make up a right-side part of the wearing band; a left-side extending section configured to make up a left-side part of the wearing band; a movable section configured to make up a part of a rear side of the wearing band, link a rear section of the right-side extending section with a rear section of the left-side extending section, and be movable relative to the right-side extending section and the left-side extending section in a retracting direction in which the length of the wearing band is decreased and in an extending direction in which the length of the wearing band is increased; a locking mechanism capable of switching the wearing band between an unlocked state in which movements of the movable section in the extending direction and the retracting direction are allowed and a locked state in which a movement of the movable section at least in the extending direction is restricted; and a first manipulating member arranged on the movable section and positioned at a part of the rear side of the wearing band, the first manipulating member being able to be manipulated by the user, wherein the movable section is configured to be driven at least in the retracting direction in the unlocked state and moved in the retracting direction when the first manipulating member rotates in a retracting rotational direction, the locking mechanism switches the wearing band from the unlocked state to the locked state when the first manipulating member rotates in the retracting rotational direction, and wherein the locking mechanism restricts the rotation of the first manipulating member in an extending rotational direction in both the locked state and the unlocked state. a main body in which a display is built; a wearing band extending from the main body to a rear side and having a shape enclosing a head of a user as a whole; a right-side extending section configured to make up a right-side part of the wearing band; a left-side extending section configured to make up a left-side part of the wearing band; a movable section configured to make up a part of a rear side of the wearing band, link a rear section of the right-side extending section with a rear section of the left-side extending section, and be movable relative to the right-side extending section and the left-side extending section in a retracting direction in which the length of the wearing band is decreased and in an extending direction in which the length of the wearing band is increased; a locking mechanism capable of switching the wearing band between an unlocked state in which movements of the movable section in the extending direction and the retracting direction are allowed and a locked state in which a movement of the movable section at least in the extending direction is restricted; and a first manipulating member arranged on the movable section and positioned at a part of the rear side of the wearing band, the first manipulating member being able to be manipulated by the user, wherein the movable section is configured to be driven at least in the retracting direction in the unlocked state and moved in the retracting direction when the first manipulating member rotates in a retracting rotational direction, the locking mechanism switches the wearing band from the unlocked state to the locked state when the first manipulating member rotates in the retracting rotational direction, and wherein the locking mechanism restricts the rotation of the first manipulating member in an extending rotational direction in both the locked state and the unlocked state.