Lectin is extracted from seeds of bitter gourd (also known as balsam pear
or Momordica charantia). A blood type checking reagent for checking a
blood type includes the lectin. The lectin extracted from seeds of bitter
gourd preferably has a molecular weight between 100,000 and 170,000
measured with polyacrylamide gel electrophoresis in existence of sodium
dodecyl sulfate (SDS-PAGE). A method of checking a blood type includes
the steps of: extracting lectin from seeds of bitter gourd (also known as
balsam pear or Momordica charantia); preparing a blood type checking
reagent containing the lectin; and checking a blood type using the blood
type checking reagent.