An apparatus for producing a three-dimensional multilayer object which produces a three-dimensional multilayer object by partially applying energy to a conductive powder and thereby melting or sintering and curing the conductive powder, the apparatus comprising: a holding unit configured to hold the conductive powder, and holding the cured three-dimensional multilayer object; a regulation unit configured to level an upper surface of the conductive powder held by the holding unit; a regulation unit moving mechanism configured to relatively move the regulation unit with respect to the conductive powder; an energy application unit configured to apply energy to the conductive powder held by the holding unit; a probe (16, 31) disposed spaced apart from a surface layer portion of the cured three-dimensional multilayer object and configured to detect a flaw in the surface layer portion; a probe moving mechanism configured to relatively move the probe (16, 31) with respect to the surface layer portion; and wherein the probe (16, 31) extending in a second direction intersecting a first direction and contains a plurality of coil units (20, 21, 22) disposed side by side in the second direction, wherein the first direction is a direction in which the regulation unit is movable, wherein the probe moving mechanism includes a first guide rail extending in the first direction and a second guide rail extending in the second direction, wherein the probe moving mechanism is configured to move the second guide rail along the first guide rail and to move the probe along the second guide rail, wherein each of the coil units includes an excitation coil configured to generate an eddy current in the surface layer portion, and a pair of detection coils disposed side by side inside the excitation coil and configured to detect a change in a magnetic field of the surface layer portion, and wherein the plurality of coil units are disposed along a virtual straight line, the straight line is obliquely disposed with respect to the first direction and the second direction, wherein the plurality of the coil units are disposed at different positions in the second direction, respectively, and wherein when viewed from a third direction, which intersect the first and second directions, the pair of detection coils are disposed adjacent to each other in the first direction in a state where the positions thereof in the second direction are offset from each other such that portions thereof overlap each other and remaining portions do not overlap each other in the second direction. a holding unit configured to hold the conductive powder, and holding the cured three-dimensional multilayer object; a regulation unit configured to level an upper surface of the conductive powder held by the holding unit; a regulation unit moving mechanism configured to relatively move the regulation unit with respect to the conductive powder; an energy application unit configured to apply energy to the conductive powder held by the holding unit; a probe (16, 31) disposed spaced apart from a surface layer portion of the cured three-dimensional multilayer object and configured to detect a flaw in the surface layer portion; a probe moving mechanism configured to relatively move the probe (16, 31) with respect to the surface layer portion; and wherein the probe (16, 31) extending in a second direction intersecting a first direction and contains a plurality of coil units (20, 21, 22) disposed side by side in the second direction, wherein the first direction is a direction in which the regulation unit is movable, wherein the probe moving mechanism includes a first guide rail extending in the first direction and a second guide rail extending in the second direction, wherein the probe moving mechanism is configured to move the second guide rail along the first guide rail and to move the probe along the second guide rail, wherein each of the coil units includes an excitation coil configured to generate an eddy current in the surface layer portion, and a pair of detection coils disposed side by side inside the excitation coil and configured to detect a change in a magnetic field of the surface layer portion, and wherein the plurality of coil units are disposed along a virtual straight line, the straight line is obliquely disposed with respect to the first direction and the second direction, wherein the plurality of the coil units are disposed at different positions in the second direction, respectively, and wherein when viewed from a third direction, which intersect the first and second directions, the pair of detection coils are disposed adjacent to each other in the first direction in a state where the positions thereof in the second direction are offset from each other such that portions thereof overlap each other and remaining portions do not overlap each other in the second direction.