Seam fabric for a machine for producing web material, in particular paper or paperboard, includes a basic structure constructed as seam cloth with weft threads running in a belt longitudinal direction and warp threads running in a belt transverse direction. At the belt longitudinal ends the weft threads form seam loops for joining the belt longitudinal ends. At least two weft thread layers are formed in the seam cloth, and weft thread pairs include respectively one weft thread of a first of the weft thread layers and one weft thread of a second of the weft thread layers. Two different types of groups of weft thread pairs are formed. In a first type of groups of weft thread pairs one respective weft thread of the first of the weft thread layers lies offset in a first direction in relation to the pair-wise assigned weft thread of the second of the weft thread layers. In the second type of groups of weft thread pairs one respective weft thread of the first of the weft thread layers lies offset in a second direction inverse to the first direction in relation to the pair-wise assigned weft thread of the second of the weft thread layers.