A two-part hair dye including a first part containing an alkali agent, a second part containing hydrogen peroxide, and a non-aerosol foamer container； wherein a liquid mixture contains Components (A) and (B) specified below, wherein the content of hydrogen peroxide in the liquid mixture is 3.60 mass% or higher, and the viscosity of the liquid mixture is 1 to 300 mPa·s. A method for dying hair, wherein a foam of the liquid mixture of the first part and the second part of the two-part hair dye is applied to hair, left to stand for 3 to 60 minutes, and then washed out. Component (A): oxidation dye； Component (B): 0.50 to 3.0 mass% of polypropylene glycol having a weight-average molecular weight of 200 to 800.
