A collimator includes a plurality of first plate-shaped parts, and a plurality of second plate-shaped parts interlocking with the plurality of first plate-shaped parts. Each of the plurality of first plate-shaped parts and the plurality of second plate-shaped parts arranged with a rectangular spacing therebetween and form a grid-like pattern. Each of the first plate-shaped parts comprises a first slotted plate part having a plurality of first slits formed thereon that is fixed to each of the second plate-shaped parts. A second slotted plate part having a plurality of second slits formed thereon is coupled to a side of the second plate-shaped parts opposite to the first slotted plate part. An adjustment plate part is disposed between the first slotted plate part and the second slotted plate part.
