We define an sl(N) analog of Onsager's algebra through a finite set of
relations that generalize the Dolan-Grady defining relations for the
original Onsager's algebra. This infinite-dimensional Lie algebra is s
hown to be isomorphic to a fixed-point subalgebra of sl(N) loop algebr
a with respect to a certain involution. As the consequence of the gene
ralized Dolan-Grady relations a Hamiltonian linear in the generators o
f sl(N) Onsager's algebra is shown to possess an infinite number of mu
tually commuting integrals of motion.