String field theory with spacetime supersymmetry

The gauge-invariant field theory of the free spinning strings with spacetime supersymmetry is presented. The supersymmetry is realized by making use of the fermion-emission vertex operator constructed by Friedan, Shenker, and Martinec and by Knizhnik. This model reproduces the spectra of the Neveu-Schwarz-Ramond model to all orders of excitation levels. It is explained in detail how to deal with the zero mode of the commuting ghost coordinates which emerges in the Ramond sector. (orig.)