A holding device includes a plate-shaped member, a tubular member, and a connecting member. The tubular member is made of ceramic and is joined to plate-shaped member at an end thereof. The tubular member has, at an other end thereof, a flange portion having a first through-hole. The connecting member is disposed on the other side of the tubular member and has, in a third surface, which is an end face of the connecting member, a hole into which a fastening member inserted through the first through-hole in the flange portion is to be screwed. A specific portion, which is a portion in an outer edge line of a fourth surface of the tubular member, the portion overlapping a minimum virtual circle covering the fourth surface, is not in contact with the third surface of the connecting member.