A toner for developing electrostatic image comprising a toner particle containing a binding resin is disclosed. which, and In the toner the binding resin has a domain-matrix structure composed of a high elastic resin composing a domain and a low elastic resin composing a matrix, an arithmetic mean value of ratio (L/W) of the Length L to Width W of the domains is 1.5 to 5.0, domains having Length L in the range of 60 to 500 nm exist 80 number % or more, and domains having Width Win the range of 45 to 100 nm exist 80 number % or more, in a viscoelastic image of a cross section of the toner particle observed via an atomic force microscope.