Analytical results for trace elements in biological sample can provide useful information to prove that a victim had taken toxic inorganic elements. In this study, we aimed to establish a detection method to detect toxic elements in a blood stain. Simulated blood samples prepared by mixing thallium standard solution in horse hemolysis blood were dropped and dried on a filter paper. Micro X-ray fluorescence spectrometry and scanning electron microscopy/energy dispersive X-ray analysis could detect only major elements in the blood stain but not the added thallium. Laser ablation-inductively coupled plasma mass spectrometry made it possible to detect those elements in the blood stain. Calibration curve obtained by measuring filter paper made from aqueous solution or horse hemolysis blood containing thallium exhibited good linear relationship in the range of 0～500 ng/mL. The present method can be used for the qualitative screening of toxic elements in blood stains.