The present invention is directed to provide an 
etching agent for a 
semiconductor substrate, which is capable of 
etching a 
titanium (Ti)-based 
metal film or a 
tungsten (W)-based 
metal film on a 
semiconductor substrate and an 
etching method using relevant etching agent, and relates to a liquid for preparing the etching agent for a 
semiconductor substrate composed of a solution comprising (A) 
hydrogen peroxide, (B) a phosphonic acid chelating agent having a hydroxyl group, (C) a basic compound, and (D-1) a 
copper anticorrosive and / or (D-2) 0.01 to 3% by weight of two or more kinds of anion species other than phosphonic acid chelating agents having a hydroxyl group, in which anion species have no oxidizing power, an etching method characterized by etching a 
titanium (Ti)-based 
metal film or a 
tungsten (W)-based metal film on a semiconductor substrate using relevant etching agent for a semiconductor substrate, further, a solution comprising (B) a phosphonic acid chelating agent having a hydroxyl group, (C) a basic compound, and (D-1) a 
copper anticorrosive and / or (D-2) anion species other than phosphonic acid chelating agents having a hydroxyl group, in which anion species have no oxidizing power.