Two matrices $$H_1$$
H
1
and $$H_2$$
H
2
with entries from a multiplicative group G are said to be monomially equivalent, denoted by $$H_1\cong H_2$$
H
1
≅
H
2
, if one of the matrices can be obtained from the other via a sequence of row and column permutations and, respectively, left- and right-multiplication of rows and columns with elements from G. One may further define matrices to be Hadamard equivalent if $$H_1 \cong \phi (H_2)$$
H
1
≅
ϕ
(
H
2
)
for some $$\phi \in \mathrm {Aut}(G)$$
ϕ
∈
Aut
(
G
)
. For many classes of Hadamard and related matrices, it is straightforward to show that these are closed under Hadamard equivalence. It is here shown that also the set of Butson-type Hadamard matrices is closed under Hadamard equivalence.