First to third guide members have first to third axis lines, and the first to third axis lines are arranged in parallel with each other. A first lens holder has a first lens held by a first lens holding portion with a first main sliding portion guided by sliding on the first guide member, and a first sub sliding portion guided by sliding on the third guide member. A second lens holder has a second lens held coaxially with the first lens by a second lens holding portion with a second main sliding portion guided by sliding on the second guide member, and a second sub sliding portion guided by the third guide member.