A fluid heating device of an engine which includes a heat radiation pipe and is configured so that heat of the heat radiation pipe is radiated to a fluid passing through an inside of the heat radiation pipe, the device comprising: an induction heating coil for inductively heating the heat radiation pipe, wherein: a holder is included, and the induction heating coil is supported by the heat radiation pipe via the holder, the holder includes a case-shaped holder and a tubular holder, the case-shaped holder includes a tubular case peripheral wall and case end walls (17b, 17c) provided at both end parts in an axial length direction of the case-shaped holder, the heat radiation pipe is penetrated through both the case end walls (17b, 17c), and the case-shaped holder is supported by the heat radiation pipe via both the case end walls (17b, 17c), the tubular holder 16 is attached to the case-shaped holder inside the case-shaped holder, the induction heating coil is attached to the tubular holder inside the case-shaped holder, and inside the case-shaped holder, the heat radiation pipe is concentrically surrounded from an outer periphery by the tubular holder and the induction heating coil on the outside of the tubular holder, characterised in that, a first heat insulating air layer is provided between the heat radiation pipe and the tubular holder, a second heat insulating air layer is provided between the tubular holder and the peripheral wall of the case-shaped holder, and the induction heating coil is housed inside the second heat insulating air layer. an induction heating coil for inductively heating the heat radiation pipe, wherein: a holder is included, and the induction heating coil is supported by the heat radiation pipe via the holder, the holder includes a case-shaped holder and a tubular holder, the case-shaped holder includes a tubular case peripheral wall and case end walls (17b, 17c) provided at both end parts in an axial length direction of the case-shaped holder, the heat radiation pipe is penetrated through both the case end walls (17b, 17c), and the case-shaped holder is supported by the heat radiation pipe via both the case end walls (17b, 17c), the tubular holder 16 is attached to the case-shaped holder inside the case-shaped holder, the induction heating coil is attached to the tubular holder inside the case-shaped holder, and inside the case-shaped holder, the heat radiation pipe is concentrically surrounded from an outer periphery by the tubular holder and the induction heating coil on the outside of the tubular holder, a holder is included, and the induction heating coil is supported by the heat radiation pipe via the holder, the holder includes a case-shaped holder and a tubular holder, the case-shaped holder includes a tubular case peripheral wall and case end walls (17b, 17c) provided at both end parts in an axial length direction of the case-shaped holder, the heat radiation pipe is penetrated through both the case end walls (17b, 17c), and the case-shaped holder is supported by the heat radiation pipe via both the case end walls (17b, 17c), the tubular holder 16 is attached to the case-shaped holder inside the case-shaped holder, the induction heating coil is attached to the tubular holder inside the case-shaped holder, and inside the case-shaped holder, the heat radiation pipe is concentrically surrounded from an outer periphery by the tubular holder and the induction heating coil on the outside of the tubular holder, characterised in that, a first heat insulating air layer is provided between the heat radiation pipe and the tubular holder, a second heat insulating air layer is provided between the tubular holder and the peripheral wall of the case-shaped holder, and the induction heating coil is housed inside the second heat insulating air layer.