The structure and magnetic properties of La(Fe1-xMnx)11.4Al1.6 (0≤ x ≤0.25) compounds have been studied. The NaZn13-type structure is preserved and the lattice parameter increases linearly with increasing the Mn concentration.The magnetic ground state changes from the antiferromagnetic to the spin-glass or the cluster-glass state by the substitution of Mn for Fe. Furthermore, a field-induced transition from cluster glass to ferromagnet is found for the samples with x=0.05 and 0.10.