A lens system includes a tubular vibrating member that vibrates due to an input drive signal; a case accommodating the vibrating member; a fluid that fills the case and immerses the vibrating member; and a pressure mitigating member that is installed in a gap between the vibrating member and the case, further outward than the vibrating member. A foam body made of fluororubber and having a large number of closed cells is used as the pressure mitigating member.