AbstractThe concept of electromotive field appears in various applications in space and astrophysical plasmas. A review is given on the electromotive field highlighting our current understanding of the theoretical picture and the spacecraft observations in interplanetary space. The electromotive field is a key concept to successfully close the set of turbulent magnetohydrodynamic equations and also to construct a more complete picture of space plasma turbulence. Applications to astrophysical cases (Earth magnetosphere, heliospheric shocks, interstellar medium, and relativistic jets) are also briefly introduced, as well.