In one embodiment, a supporting case includes a lower case member and an upper case member. The mounting substrate is pinched between a lower cylindrical supporting portion and a upper cylindrical supporting portion. Peripheral regions of the mounting substrate that are on a peripheral side with respect to a part pinched between the lower cylindrical supporting portion and the upper cylindrical supporting portion are positioned in a space defined by a bottom plate portion, a lower peripheral-wall portion, and the lower cylindrical supporting portion of the lower case member and a top lid portion, an upper peripheral-wall portion, and the upper cylindrical supporting portion of the upper case member.