Provided are a rotary joint and housing segments of a rotary joint which can handle the case where, for example, the number of chemical solutions used is increased or decreased at low cost and which contribute to a reduction in production costs and lead time. A rotary joint includes a substantially cylindrical shaft (3); a shaft communicating hole (15a to 15d) formed in the shaft (3) and having an opening in a side surface thereof; a housing (7) having an insertion hole (5) where the shaft (3) is inserted so as to be capable of relative rotation; a plurality of housing segments (25, 25, and 27a to 27d) formed by dividing the housing (7) and arranged in a central-axis (C) direction of the shaft (3); a housing communicating hole (51) formed so that the shaft communicating hole (15a to 15d) communicates with the outside of the housing (7) via the housing communicating hole (51); an annular groove (49) formed so that the shaft communicating hole (15a to 15d) communicates with the housing communicating hole (51) via the annular groove (49); and an annular leakage-preventing member (43) disposed between the shaft (3) and the housing (7) to block fluid movement in the central-axis (C) direction.