The present invention relates to a prefabricated sauna apparatus which can be used as a bed with a heating function. More particularly, the prefabricated sauna apparatus comprises: a lower side unit including a lower plate frame in a rectangular shape, which is located on the bottom and has one open side, and a lower plate, which is joined to one side of the lower plate frame to be able to slide and includes an embedded heating pipe heated by hot water supplied from the outside through a hose lateral side units which are joined to the outline of the lower side unit in a perpendicular direction and an upper side unit including an upper plate, which is joined to upper portions of the lateral side units and face the lower side unit, an opening and closing plate, which is formed on one side of the upper plate and opens and closes a portion of the upper plate, and a support plate, which is located on one side of the upper plate and is formed to be able to slide on the opening and closing unit opened and closed by the opening and closing plate, and has a support groove formed thereon. Joining grooves or joining protrusions, corresponding to the joining grooves, are formed on joining portions in the lower side unit, the lateral side units, and the upper side unit to join the lower side unit, the lateral side units, and the upper side unit to each other. According to the present invention, a sauna effect can be obtained by using heat generated by heating the heat pipe embedded in the lower side unit. The prefabricated sauna apparatus can be conveniently moved by assembling and disassembling the same as the lower side unit, the lateral side units, and the upper side unit are assembled by the joining grooves and the joining protrusions formed on the joining portions. The prefabricated sauna apparatus can be used as a bed with a heating function by sliding and exposing the lower plate, in which the heating pipe is embedded, to the outside.COPYRIGHT KIPO 2016본 발명은 온열 침대 기능이 구비되
