To provide a solid electrolyte capable of efficiently making flow a lithium ion and easily manufacturing, and to provide a solid electrolyte battery, a lithium ion conductor, and its manufacturing method.

The solid electrolyte 14 contains a single crystal of a lithium ion conductor represented by compositional formula Li1+xM1xTi2-x(PO4)3 (in the formula, M1 is at least one selected from the group comprising Al, Sc, In, Fe, Cr, Ga, Y, and La, and the value of X is in a range of 0x2.0). The solid electrolyte contains a lithium ion conductor represented by compositional formula Li1+2xM2xTi2-x(PO4)3 (in the formula, M2 is at least one selected from the group comprising Zn, Si, Mn, Ge, Nd, Sr, and V; the valency of M2 is divalent, the value of x is in a range of 0x2.0). A battery using the solid electrolyte is capable of conducting quick charge.