A method for manufacturing an object to be manufactured (5; 12) by manufacturing a surface of the object to be manufactured (5; 12) to a flat surface or an arbitrary curved surface, with machining the surface of the object to be manufactured (5; 12) through a hydrolysis process in the presence of water, the method comprising: (a) placing, in a container containing machining liquid, the object to be manufactured (5; 12) and a machining reference surface (3; 10) having a conductive catalyst substance at least on its surface, with the object to be manufactured (5; 12) and the machining reference surface (3; 10) being brought into contact with or very close to each other, and immersing the object to be manufactured (5; 12) and the machining reference surface (3; 10) with the machining liquid, wherein the object to be manufactured (5; 12) is a solid oxide in which one or more kinds of elements are bonded through oxygen or a multicomponent solid oxide formed of a plurality of oxides, (b) adjusting a potential of the machining reference surface (3; 10) to a range where neither H 2 nor O 2 is produced, including a spontaneous potential, (c) allowing the object to be manufactured (5; 12) and the machining reference surface (3; 10) to be moved relatively to each other, with the object to be manufactured (5; 12) and the machining reference surface (3; 10) being brought into contact with or very close to each other, (d) wherein the machining liquid is prepared only from (i) water, or (ii) a mixture in which pure water or ultrapure water is mixed with a complex helping dissolution of the decomposition product, and wherein the machining liquid is completely free from a polishing agent or abrasive grains, (e) the catalyst substance promotes dissociation of a water molecule and impairs backbond between an oxygen atom and another atom, (f) a hydroxyl group dissociated from the water molecule is adsorbed to the surface of the object to be manufactured (5; 12) to cut the backbond, to thereby produce a decomposition product with the atoms forming the solid oxide by cutting the backbond, and a removal machining performed on the surface of the object to be manufactured (5; 12) by dissolving the decomposition product in the machining liquid selectively advances from an immediate proximity of the catalyst substance; wherein a catalyst substance surface including a transition metal element in which a d-orbital of an electron thereof is in the vicinity of Fermi level, is used as the machining reference surface. (a) placing, in a container containing machining liquid, the object to be manufactured (5; 12) and a machining reference surface (3; 10) having a conductive catalyst substance at least on its surface, with the object to be manufactured (5; 12) and the machining reference surface (3; 10) being brought into contact with or very close to each other, and immersing the object to be manufactured (5; 12) and the machining reference surface (3; 10) with the machining liquid, wherein the object to be manufactured (5; 12) is a solid oxide in which one or more kinds of elements are bonded through oxygen or a multicomponent solid oxide formed of a plurality of oxides, (b) adjusting a potential of the machining reference surface (3; 10) to a range where neither H 2 nor O 2 is produced, including a spontaneous potential, (c) allowing the object to be manufactured (5; 12) and the machining reference surface (3; 10) to be moved relatively to each other, with the object to be manufactured (5; 12) and the machining reference surface (3; 10) being brought into contact with or very close to each other, (d) wherein the machining liquid is prepared only from (i) water, or (ii) a mixture in which pure water or ultrapure water is mixed with a complex helping dissolution of the decomposition product, and wherein the machining liquid is completely free from a polishing agent or abrasive grains, (e) the catalyst substance promotes dissociation of a water molecule and impairs backbond between an oxygen atom and another atom, (f) a hydroxyl group dissociated from the water molecule is adsorbed to the surface of the object to be manufactured (5; 12) to cut the backbond, to thereby produce a decomposition product with the atoms forming the solid oxide by cutting the backbond, and a removal machining performed on the surface of the object to be manufactured (5; 12) by dissolving the decomposition product in the machining liquid selectively advances from an immediate proximity of the catalyst substance;