A two-dimensional collimator module is provided. The two-dimensional collimator module includes first collimator plates arranged in a channel direction, second collimator plates arranged in a slice direction and combined with the first collimator plates to form a lattice, and a first block and a second block that hold the first collimator plates, wherein each of the first collimator plates is formed with slits, each of the second collimator plates is inserted through an associated row of the slits, first plate surfaces of the second collimator plates in the slice direction abut only first wall surfaces of first and second wall surfaces of the slits in the slice direction in a first set of the first collimator plates, and second plate surfaces of the second collimator plates opposite to the first plate surfaces abut only the second wall surfaces of the slits in a second set of first collimator plates.
