A high-molecular-weight recombinant silk or silk-like protein having a molecular weight which is substantially similar to that of native silk protein, and a micro- or nano-sized spider silk or silk-like fiber having improved physical properties, produced therefrom. The recombinant silk or silk-like protein according to the invention has high molecular weight, like dragline silk proteins from spiders, while a fiber produced therefrom has excellent physical properties compared to a fiber produced from native silk protein. Thus, the recombinant silk or silk-like protein and the spider silk or silk-like fiber produced therefrom will be highly useful in various industrial applications, including bioengineering applications and medical applications.