A thickener for use in an alkaline battery provides a gel viscosity ratio (N1h/N12h) of 0.7 to 1.3, the gel viscosity ratio (N1h/N12h) being a ratio of a viscosity (N1h) of a gel after being left to stand for one hour to a viscosity (N12h) of the gel after being left to stand for twelve hours (where the gel viscosity is a viscosity of a gel composed of 2.0 parts by weight of the thickener, 200 parts by weight of zinc powder, and 100 parts by weight of 37 wt % aqueous solution of potassium hydroxide, measured at 40.degree. C. according to JIS K7117-1: 1999). An alkaline battery having a negative electrode gel in which the thickener of the present invention is used is provided. The alkaline battery exhibits improved long-term retention of discharge characteristics (discharge amount and discharge time), and improved impact resistance.