A method of manufacturing a rubber product by bonding a plurality of thin pieces (L1,L2,L3) on a manufacturing table , the method comprising: an adhesion prevention treatment step (S 1) of treating uncrosslinked rubber powder, which is a material of the rubber product , performed by coating the surface of the uncrosslinked rubber powder with an adhesion prevention agent, to prevent mutual adhesion of the uncrosslinked rubber powder; a first raw rubber powder supply step (S4) of supplying raw rubber powder, on which the adhesion prevention treatment has been performed, onto a surface of the manufacturing table uniformly in a layer of a thickness corresponding to a thin piece (L1); a first crosslinking step (S5) of irradiating a portion of the layer (m1) of raw rubber powder with an electron beam according to a shape corresponding to the thin piece (L1) to crosslink the portion that is irradiated; a post-treatment step (S6) of adjusting relative positions of a surface of a crosslinked portion (M1) in the layer (m1) of raw rubber powder and a surface of the manufacturing table to align the surface of the crosslinked portion (M1) with the surface of the manufacturing table ; a second raw rubber powder supply step (S7) of supplying the raw rubber powder onto the surface of the manufacturing table , including the surface of the crosslinked portion (M1), uniformly in a layer of a thickness corresponding to a next thin piece (L2) to be stacked on the thin piece (L1); and a second crosslinking step (S8) of irradiating a portion of the layer (m2) of raw rubber powder with an electron beam according to a shape corresponding to the next thin piece (L2) to crosslink the portion that is irradiated, wherein the uncrosslinked rubber powder includes calcium oxide, and wherein the post-treatment step (S6), the second raw rubber powder supply step (S7), and the second crosslinking step (S8) are sequentially repeated to bond the plurality of thin pieces (L1,L2,L3) together. an adhesion prevention treatment step (S 1) of treating uncrosslinked rubber powder, which is a material of the rubber product , performed by coating the surface of the uncrosslinked rubber powder with an adhesion prevention agent, to prevent mutual adhesion of the uncrosslinked rubber powder; a first raw rubber powder supply step (S4) of supplying raw rubber powder, on which the adhesion prevention treatment has been performed, onto a surface of the manufacturing table uniformly in a layer of a thickness corresponding to a thin piece (L1); a first crosslinking step (S5) of irradiating a portion of the layer (m1) of raw rubber powder with an electron beam according to a shape corresponding to the thin piece (L1) to crosslink the portion that is irradiated; a post-treatment step (S6) of adjusting relative positions of a surface of a crosslinked portion (M1) in the layer (m1) of raw rubber powder and a surface of the manufacturing table to align the surface of the crosslinked portion (M1) with the surface of the manufacturing table ; a second raw rubber powder supply step (S7) of supplying the raw rubber powder onto the surface of the manufacturing table , including the surface of the crosslinked portion (M1), uniformly in a layer of a thickness corresponding to a next thin piece (L2) to be stacked on the thin piece (L1); and a second crosslinking step (S8) of irradiating a portion of the layer (m2) of raw rubber powder with an electron beam according to a shape corresponding to the next thin piece (L2) to crosslink the portion that is irradiated, wherein the uncrosslinked rubber powder includes calcium oxide, and wherein the post-treatment step (S6), the second raw rubber powder supply step (S7), and the second crosslinking step (S8) are sequentially repeated to bond the plurality of thin pieces (L1,L2,L3) together. <EOS>