Abstract: A process of producing a polymer alloy includes melt-kneading at least two incompatible crystalline resins in a supercooled state by chaotic mixing using a twin-screw extruder. A polymer alloy obtained by melt-kneading at least two incompatible crystalline resins has a dispersed structure that particles dispersed in the polymer alloy have an average particle size of 0.001 to 1 ?m, wherein in scattering measurement, (a) a peak half-width in a spectrum obtained by plotting scattering intensity against the wavenumber of scattered light and (b) a maximum wavenumber of the peak satisfy: 0<(a)/(b)?1.5.