A tilt angle adjusting device has a shaft configured to be fixed to a bottom surface of a housing at least one end, and a moment transmission member connected to the shaft. The moment transmission member allows relative rotation between the shaft and the moment transmission member when a moment equal to or more than a predetermined value is applied about an axis of the shaft from the housing, and restricts the relative rotation when the moment is released. The moment transmission member includes a leg configured to be placed on a surface on which the housing is installed. The leg is provided with part of a bearing to support the shaft. The moment transmission member also includes a plate member to press an outer peripheral surface of the shaft. The plate member forms the rest of the bearing.