We clarify the group-theoretical structure of N=1 and N=2 two-form sup
ergravity, which is classically equivalent to the Einstein supergravit
y. N=1 and N=2 two-form supergravity theories can be formulated as gau
ge theories. By introducing two Grassmann variables theta(A) (A=1,2),
we construct the explicit representations of the generators Q(i) of th
e-gauge group, which makes it possible to express any product of the g
enerators as a linear combination of the generators Q(i)Q(j)=Sigma(k)f
(k)(ij)Q(k). By using the expression and the tensor product representa
tion, we show how to construct finite-dimensional representations of t
he gauge groups. Based on these representations, we construct the Lagr
angians of N=1 and N=2 two-form supergravity theories.