Abstract: A plate connecting assembly according to an embodiment includes a first frame, with an upper portion and a lower portion of the first frame making a predetermined angle with each other, and a second frame having a first support portion facing the upper portion and a second support portion facing the lower portion. In the plate connecting assembly, a first fixation-subject object is fixed between the upper portion and the first support portion, a second fixation-subject is fixed between the lower portion and the second support portion, and thus the first and second fixation-subject objects are fixed in such a manner that an angle therebetween is the same as an angle that the upper portion and the lower portion make with each other.