A secret sharing method in which secret data is shared as shared data parts (A, B, C) equal to or greater than a threshold value (k) in number such that the secret data cannot be reconstructed from shared data parts (A, B, C) less than the threshold value (k) in number, comprising the steps of: generating a plurality of groups (R, S) equal to or greater than the threshold value (k) in number, one of the groups having at least parts of unpublished data pieces (R1-R5), and another one of the groups having at least parts of secret data pieces (S1-S4) derived from the secret data; creating from said plurality of groups a plurality of shared data parts (A, B, C), each of which having shared data pieces (Ai, Bi, Ci), wherein at least parts of the shared data pieces (A1-A4, B2-B5, C3-C5) are created by combining at least parts of the unpublished data pieces (Ri) and at least parts of the secret data pieces (Si), by combining the created shared data pieces (Ai, Bi, Ci) into the plurality of shared data parts, including first shared data parts and second shared data parts, equal to or greater than the threshold value (k) in number; wherein at least parts of the shared data pieces (A2-A4) combined into the first shared data parts are created based on first combinations (R2-S2, R3-S3, R4-S4) of at least parts of the unpublished data pieces (R1-R4) in a given order and at least parts of the secret data pieces (S1-S4) in a given order, and at least parts of the shared data pieces (B2-B5) combined into the second shared data parts are created based on second combinations (R2-S1, R3-S2, R4-S3, R5-S4), different from the first combinations, of at least parts of the unpublished data pieces (R2-R5), in the given order, that were used to create the first shared data parts (A2-A4) and at least parts of the secret data pieces (S1-S4), in the given order, that were used to create the first shared data parts (A2-A4). generating a plurality of groups (R, S) equal to or greater than the threshold value (k) in number, one of the groups having at least parts of unpublished data pieces (R1-R5), and another one of the groups having at least parts of secret data pieces (S1-S4) derived from the secret data; creating from said plurality of groups a plurality of shared data parts (A, B, C), each of which having shared data pieces (Ai, Bi, Ci), wherein at least parts of the shared data pieces (A1-A4, B2-B5, C3-C5) are created by combining at least parts of the unpublished data pieces (Ri) and at least parts of the secret data pieces (Si), by combining the created shared data pieces (Ai, Bi, Ci) into the plurality of shared data parts, including first shared data parts and second shared data parts, equal to or greater than the threshold value (k) in number; wherein at least parts of the shared data pieces (A2-A4) combined into the first shared data parts are created based on first combinations (R2-S2, R3-S3, R4-S4) of at least parts of the unpublished data pieces (R1-R4) in a given order and at least parts of the secret data pieces (S1-S4) in a given order, and at least parts of the shared data pieces (B2-B5) combined into the second shared data parts are created based on second combinations (R2-S1, R3-S2, R4-S3, R5-S4), different from the first combinations, of at least parts of the unpublished data pieces (R2-R5), in the given order, that were used to create the first shared data parts (A2-A4) and at least parts of the secret data pieces (S1-S4), in the given order, that were used to create the first shared data parts (A2-A4).