To prepare basic monomers stabilized in color such as N,N- dialkylaminoalkyl (meth)acrylates (e.g. dimethylaminoethyl acrylate) or N,N- dialkylaminoalkyl (meth)acryamides and to provide both a method for preparing the basic monomers and a method for handling thereof.

At least one of an amide group-containing compound, phosphorous esters, phosphoric esters and phosphines and at least one of a phenolic compound represented by the formula (R5, R6, R8 and R9 denote each independently hydrogen atom or a 1-4C alkyl group; R7 denotes hydrogen atom, a 1-4C alkyl group or a 1-4C alkoxy group) are added to basic monomers. The resultant basic monomers stabilized in color are handled under conditions so as to provide 0.01-10vol.% oxygen concentration thereof in the vapor phase part.