To secure reliability as in a conventional manner even when using lead-free solder.

High temperature solder consisting of the composition of silver, copper and tin is used for solder 33 used at the time of mounting an electronic part on a circuit board 22, and the circuit board 22 is positioned so as to be slightly movable by a level by which the movement of another movable member is not hindered. The base material of the circuit board 22 is formed of an epoxy resin incorporating glass, and the composition ratio of the high temperature solder is set as over 5.0 wt.% and ≤9.5 wt.% of the silver, ≤0.9 wt.% of the copper and the remaining ratio of the tin. Thus, even though the lead-free solder is used in a film unit with a lens 2, the deterioration of a quality is not caused, so that the reliability as in the conventional manner is secured.