The effect of N-vinylpyrrolidone (3% by mass) was compared with those of corn. adhesion promoters on shear strength (cohesion), peel adhesion, tack (stickiness), and shrinkage of the pressure-sensitive adhesives (PSA) produced by radical copolymerization of an EtOAc-dild. mixt. of 2-ethylhexyl acrylate, Bu acrylate and acrylic acid at boiling. The PSA composition with N-vinylpyrrolidone promotess showed the higher adhesion and tack than that with com. promoters at optimum shrinkage and cohesion values.