NOVELTY - Reaction device comprises: reaction device main body including first reaction unit (11) which performs reaction of first reaction material, and second reaction unit (12) which performs reaction of second reaction material; first heater which heats first reaction unit at first temperature; second heater which heats second reaction unit at second temperature; heat reflective film (32a); heat releasing portion (40) which transmits or absorbs at least a part of heat ray radiated from reaction device main body; and container which houses reaction device main body in it.    USE - The reaction device is useful in fuel cell device which is used in e.g. lap-top personal computer, mobile phone, personal digital assistant, an electronic notebook, and electronic apparatus.    ADVANTAGE - The reaction device: maintains temperature difference between reaction units; reduces manufacturing steps and time; allows sealed space to kept at high sealed state, thus burden to keep sealed state is simplified; exhibits desirable temperature difference; and improves or maintains degree of vacuum of sealed chamber.    DETAILED DESCRIPTION - Reaction device comprises: a reaction device main body including a first reaction unit (11) which performs reaction of a first reaction material, and a second reaction unit (12) which performs reaction of a second reaction material; a first heater which heats the first reaction unit at a first temperature; a second heater which heats the second reaction unit at a second temperature lower than the first temperature; a heat reflective film (32a), provided to oppose an external surface of the reaction device main body, and to reflect a heat ray that is radiated from the reaction device main body; a heat releasing portion (40) which transmits or absorbs at least a part of the heat ray radiated from the reaction device main body; and a container which houses the reaction device main body in it and has a lower heat ray reflectivity than a heat ray reflectivity of the heat reflective film, where the heat reflective film is provided on an internal wall surface of the container, and the heat reflective film includes a first portion which is exposed and which is opposed to the first reaction unit, and a second portion which is opposed to the second reaction unit and at which the heat releasing portion is provided.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of the reaction device.    First reaction unit (11)    Second reaction unit (12)    Heat reflective film (32a)    Heat absorbing film (32b)    Heat releasing portion (40)