The present invention provides a replaceable brush for an electric toothbrush in which the thickness of a head part is made thin, and thereby, it is possible to obtain an increased cleaning sensation with respect to back teeth, and at the same time, it is possible to reduce an unpleasant sensation caused by vibration within the oral cavity. The replaceable brush for an electric toothbrush of the present invention is a replaceable brush (1B) for an electric toothbrush including a head part (4) and a neck part (3) detachably attached to a toothbrush body including a handle part of the electric toothbrush, wherein the maximum thickness (T) of the head part (4) ranges from 2 mm to 4 mm, the minimum thickness (D) of the neck part (3) ranges 3 mm to 5 mm, and a relationship of D ≥ T is satisfied, and wherein at a back side of the neck part (3) and at a side of the head part (4) which is the opposite side to a front side at which a bristle-tufted face (4a) is provided, the head part (4) is formed by biasing in the direction toward the front side from the back side as compared to the neck part (3).一種電動牙刷用替換刷頭以及電動牙刷，所述電動牙刷用替換刷頭藉由使頭部的厚度變薄而能夠獲得高的臼齒清掃實感，並且減輕在口腔內的振動所引起的不適感。本發明的電動牙刷用替換刷頭為拆裝自如地安裝於電動牙刷的包含柄部的牙刷本體且包含頸部（3）及頭部（4）的電動牙刷用替換刷頭（1B），頭部（4）最大厚度（T）為2 mm～4 mm，頸部（3）最小厚度（D）為3 mm～5 mm，且滿足D≧T的關係，於設置有植毛面（4a）前表面側的相反側的頭部（4）及頸部（3）的背面側，頭部（4）相較於頸部（4）設置為自背面側朝前表面側的方向偏移。
