The present invention provides alumina hydrate particles, a flame retardant and a resin composition that are each for an electric wire/cable covering material improvable in flame retardancy and mechanical properties while the covering material keeps acid resistance; such an electric wire/cable; and producing methods thereof. The alumina hydrate particles of the present invention for electric wire/cable covering material have an average particle size of 0.5 to 2.5 μm, and having a primary particle variation R of 24% or less, the variation R being represented by the following expression: primary particle variation R (%)=“standard deviationσ(μm) of major axis diameters of the primary particles”/“average value(μm) of the major axis diameters of the primary particles”×100.