The present invention relates to a far-infrared radiant heating device and, more specifically, to a far-infrared radiant heating device capable of effectively maintaining the temperature of a large area of the inside of a greenhouse by forming a wide radiation angle of a far-infrared ray having strong straightness. The far-infrared radiant heating device according to the present invention comprises: a heater formed in a pipe shape and generating heat by receiving electricity from an external power source； a heating plate having a far-infrared radiation coating layer on an outer surface thereof exposed to the outside, a heater engagement part on an inner surface thereof to protrude along the longitudinal direction so the heater is mounted, and first fastening ribs on inner surfaces thereof placed on both sides in the width direction to be bent and protrude along the longitudinal direction； a main body part having a side wall formed on both sides thereof along the longitudinal direction to form a receiving space therein and having an open upper part； a support plate received and fixed in the receiving space of the main body part and having second fastening ribs corresponding to the first fastening ribs on both ends thereof in the width direction so the first fastening ribs are slidingly engaged； and a reflective plate disposed at a lower part of the support plate, received and fixed in the receiving space of the main body part, and reflecting heat generated in the heater toward the heating plate, wherein the heating plate comprises a flat part formed to be flat and an inclined part extended while being inclined downward from both ends in the width direction of the flat part.본 발명은 원적외선 복사난방장치에 관한 것으로, 구체적으로는 직진성이 강한 원적외선의 방사각이 넓게 형성되도록 함으로써 비닐 하우스 내부의 넓은 면적의 온도를 효율적으로 유지할 수 있는 원적외선 복사난방장치에 관한 것이다.본 발명은 파이프 형태로 이루어지고, 외부 전원으로부터 전기를 공급받아 열을 발생시키는 히터； 외부로 노출되는 외면에는 원적외선 방사 코팅층이 형성되고, 내면에는 상기 히터가 안착되도록 히터 결합부가 길이 방향을 따라 돌출 형성되며, 폭 방향 양측에 위치한 내면에는 길이 방향을 따라 제1체결리브가 절곡되어 각
