To provide a filler for solid-phase extraction having excellent recovery to both hydrophobic material and ionic material by having hydrophobicity and an ion-exchange group together, a solid-phase extraction method using the filler, a packed device using the filler, and a sample treating method.

This filler for solid-phase extraction is characterized by using particles having the ion-exchange group introduced without damaging a hydrophobic part, prepared by introducing the ion-exchange group into the particles obtained by copolymerization between a hydrophobic monomer (A) and a hydrophilic monomer (B). This solid-phase extraction method, the packed device for solid-phase extraction, and the sample treating method using it are also provided.