Abstract: The present invention is intended to provide a metal scavenger that is free from the defects of metal scavengers formed by introducing dithioic acid groups to polyalkylenepolyamines or the like, is high in settling speed of flock when used in waste water treatment, and can carry out treatment of waste water efficiently and also to provide a process of producing the same efficiently. The present metal scavenger has a structure that is formed by replacing the hydrogen atoms linked to the nitrogen atoms of a polyamine having aminomethyl groups by dithioic acid groups or their salts and that is represented by the following general formula: ##STR1## wherein R represents a dithioic acid group, an alkali metal dithioate group, an alkaline earth metal dithioate group, or an ammonium dithioate group and R' represents a hydrogen atom, a dithioic acid group, an alkali metal dithioate group, an alkaline earth metal dithioate group, or an ammonium dithioate group.