Disclosed are a dehumidification apparatus, and an air conditioning apparatus and system having the same. The dehumidification apparatus includes: a desiccant rotor having a desiccant for adsorbing moisture; and a regeneration unit disposed at one side of the desiccant rotor, for desorbing the moisture adsorbed to the desiccant. The regeneration unit includes at least one of a hollow hot water line containing hot water exchanging heat with the air flowing toward the desiccant rotor. The dehumidification apparatus efficiently reproduces the desiccant for dehumidification and air conditioning.