The demand for lithium secondary batteries having more safety and energy density is high. In this aspect, lithium ion batteries including typical liquid electrolytes have fundamental limitations. Liquid electrolytes can cause a fire or explosion of battery and decomposition of them at high potential obstructs applying high potential cathode. Applying solid electrolyte can solve these limitations so many solid electrolytes have been interested in and researched. Major types of solid electrolytes are sulfides and oxides and their pros and cons are obvious. It is commonly known that sulfides have advantages of high ionic conductivity and softness for easy contact, while oxides have high electrochemical stability. One of the tactics that fulfill high energy density is using lithium metal directly as anode and the researches that using lithium metal on solid electrolyte are progressed. Major oxide solid electrolytes not including transition metal had been considered stable with lithium metal. However, increased resistances of lithium symmetric cell with time and all solid-state cell after charge and discharge were observed and interphase reactions with lithium metal were calculated from some solid electrolytes. However, the relationship between them and the failure mechanism of the solid electrolytes with lithium metal are not fully understood yet. In this research, we discuss the phenomena from the interphase between lithium metal and solid electrolytes; lithium aluminum germanium phosphate (LAGP) and lithium lanthanum zirconium oxide (LLZO). We also suggest the mechanism of increased resistance with direct contact of lithium metal and the solid electrolyte.