A chemical analyzer in which a component of a material to be analyzed acts on a coloring (dye forming) reagent in a reagent layer of the multi-layer type chemical analysis slide. The material to be analyzed is then maintained at a constant temperature for a predetermined period of time, after which the degree of coloration thereof is measured optically so that predetermined parameters of the material are measured with a very high accuracy. A conveying mechanism conveys the chemical analysis slides along an analysis path between two stationary temperature control plates. A first one of the plates having a cut therein has a heating element buried therein extending throughout the plate. The opposed plate has a heating element extending into regions not opposed by the cut in the first plate. The second plate has plural openings through which an irradiating light beam from a light source of a photometric mechanism and a reflection light beam from slides positioned over the openings pass. The lower plate has corresponding reference reflection plates at positions which are irradiated by the irradiating light beam.