To provide an adsorption agent easy to handle while maintaining adsorptivity of a cellulose nanofiber without requiring a treatment at a high temperature to obtain the adsorption agent, a manufacturing method of the adsorption agent, and a wallpaper containing the adsorption agent.SOLUTION: An adsorption agent 5 includes at least one kind of a polymer particle 3 and a fine cellulose 1 covering at least part of a surface of the polymer particle 3, and contains a composite particle in which the polymer particle 3 and the fine cellulose 1 are in an inseparable state.SELECTED DRAWING: Figure 1【課題】吸着剤を得るために高温での処理を必要とせず、セルロースナノファイバーの吸着性を維持しつつ、取り扱いが容易である吸着剤及びその吸着剤の製造方法並びにその吸着剤を含んだ壁紙を提供すること。【解決手段】本発明の一態様に係る吸着剤5は、少なくとも一種類のポリマー粒子3と、ポリマー粒子3の表面の少なくとも一部を覆う微細化セルロース1とを有し、ポリマー粒子3と微細化セルロース1とが不可分の状態にある複合粒子を含んだことを特徴とする。【選択図】図1