A biochemistry analyzer includes, an attenuated total reflection prism, a sample cell disposed on a surface of the prism, a sample supplier, a device for disposing more objective molecules in the liquid sample to a near portion of the sample which is near the surface of the prism, an infrared light source for generating an infrared light which is transmitted to the attenuated total reflection prism, a detector for detecting the infrared light which is reflected from the prism after the far portion of the sample is solidified, and a computer for calculating signals from the detector. As the objective molecules are gathered near the prism, accuracy of the biochemistry analyzer becomes higher.