A garnet-type solid electrolyte contains a crystal having (110) face, (1-10) face, (112) face, (1-12) face, and (11-2) face, the garnet-type solid electrolyte being Li7La3Zr2O12. A battery includes a solid electrolyte interposed between a positive and a negative electrode, the solid electrolyte being the garnet-type solid electrolyte. A method of producing a garnet-type solid electrolyte represented by a composition formula Li7La3Zr2O12 and has (110) face, (1-10) face, (112) face, (1-12) face, and (11-2) face as a crystal face, including a step of preparing a lithium-containing compound, a lanthanum-containing compound, and a zirconium-containing compound; a step of mixing these compounds such that a molar ratio among the elements satisfies Li:La:Zr=a:b:c (where a is from 120 to 160, b is from 1 to 5, and c is from 1 to 5); and a step of heating the mixture between 400 and 1,200° C.