A method for preparing a catalyst represented by the following Chemical Formula 1, comprising the steps of: mixing and stirring a metal precursor to prepare a slurry; drying the slurry at 110 °C to 130 °C for 8 to 20 hours, and grinding, kneading, and conducting first compression molding; drying the first compression molded material at 110 °C to 130 °C, and grinding and conducting second compression molding; and firing the second compression molded material at 300 °C to 500 °C, wherein the metal precursor comprises a metal and a ligand, and the ligand is one or more selected from the group consisting of NH 3, NH 2, NO X (where x is an integer of 1 to 3), Cl, F, N, OH, SO x (where x is 3 or 4), O, CO, COO, SCN, CN, NCS, ONO, C n H m O x (where n is an integer of 1 to 20, m is an integer of 1 to 40, and x is an integer of 1 to 10), and a C1-20 alkoxide, and [Chemical Formula 1] Mo 12 P a A b B c C d D e E f O g wherein, in Chemical Formula 1, A is one or more elements selected from the group consisting of W, V, Nb, and Cr; B is one or more elements selected from the group consisting of As, B, Sb, Ce, Pd, and Te; C is one or more elements selected from the group consisting of Si, Al, Zr, Rh, Cu, Ti, Ag, and Sn; D is one or more elements selected from the group consisting of Na, K, Li, Rb, Cs, Ta, Ca, Mg, Sr, and Ba; and E is one or more elements selected from the group consisting of Fe, Co, and Ni, and a, b, c, d, e, f, and g represent the atomic ratio of each element, where a is 0.5 to 2, b is 0.01 to 10, c is 0 to 15, d is 0.01 to 20, e is 0.01 to 20, f is 0.01 to 15, and g is a value determined by the oxidation state of each atom. mixing and stirring a metal precursor to prepare a slurry; drying the slurry at 110 °C to 130 °C for 8 to 20 hours, and grinding, kneading, and conducting first compression molding; drying the first compression molded material at 110 °C to 130 °C, and grinding and conducting second compression molding; and firing the second compression molded material at 300 °C to 500 °C, wherein the metal precursor comprises a metal and a ligand, and the ligand is one or more selected from the group consisting of NH 3, NH 2, NO X (where x is an integer of 1 to 3), Cl, F, N, OH, SO x (where x is 3 or 4), O, CO, COO, SCN, CN, NCS, ONO, C n H m O x (where n is an integer of 1 to 20, m is an integer of 1 to 40, and x is an integer of 1 to 10), and a C1-20 alkoxide, and [Chemical Formula 1] Mo 12 P a A b B c C d D e E f O g wherein, in Chemical Formula 1, A is one or more elements selected from the group consisting of W, V, Nb, and Cr; B is one or more elements selected from the group consisting of As, B, Sb, Ce, Pd, and Te; C is one or more elements selected from the group consisting of Si, Al, Zr, Rh, Cu, Ti, Ag, and Sn; D is one or more elements selected from the group consisting of Na, K, Li, Rb, Cs, Ta, Ca, Mg, Sr, and Ba; and E is one or more elements selected from the group consisting of Fe, Co, and Ni, and a, b, c, d, e, f, and g represent the atomic ratio of each element, where a is 0.5 to 2, b is 0.01 to 10, c is 0 to 15, d is 0.01 to 20, e is 0.01 to 20, f is 0.01 to 15, and g is a value determined by the oxidation state of each atom.