The thermal expansion coefficient (TEC) of Co_2MAl (M = Ti, V, Cr, Mn, Fe, Ni) band ferromagnets is measured in the temperature interval of 80–900 K. The magnetic-fluctuation contribution α_ m, _sf( T ) = α_ m ( T ) + α_sf( T ) to TEC comprised of negative Stoner α_ m ( T ) and positive spin-fluctuation α_sf( T ) contributions is presented. It is assumed that the contribution of α_ m ( T ) component is proportional to the square of spontaneous magnetization. The contribution of α_sf( T ) is stipulated by the effects of inducing local magnetic moments by spin fluctuations and is proportional to the Pauli susceptibility.