  We prove that weights of two Siegel modular forms of nonquadratic nebentypus
should satisfy some congruence relations if these modular forms are congruent
to each other. Applying this result, we prove that there are no mod $p$
singular forms of nonquadratic nebentypus. Here we consider the case where the
Fourier coefficients of the modular forms are algebraic integers, and we
emphasize that $p$ is a rational prime. Moreover, we construct some examples of
mod $\frak{p}$ singular forms of nonquadratic nebentypus using the Eisenstein
series studied by Takemori.
