FORMALDEHYDE DETECTING MATERIAL, FORMALDEHYDE DETECTOR, FORMALDEHYDE DETECTING METHOD AND FORMALDEHYDE DETECTING REAGENT

A formaldehyde detector (10) provided with a detecting reagent which develops a color in response to formaldehyde. The detector (10) comprises a detection element (30) having a base material (31) which constitutes an optical waveguide transmitting light via repeated total reflection and a mesoporous layer (32) which serves as the surface of the base material (31), is formed by laminating on at least a part of the light reflecting face and carries the detecting reagent as described above. Furthermore, it has a light emitting material which emits an incident light on the base material (31) and a light receiving material which receives the light outgoing from the base material (31). Furthermore, it has a signal processing section wherein the light signal from the light receiving material is received and a change in the optical properties based on the color development due to the reaction of formaldehyde with the detecting reagent is detected to thereby detect formaldehyde and measure its concentration from the change in the optical properties.