Let
H be an infinite-dimensional complex Hilbert space and let
L(H) be the algebra of all bounded linear operators on
H. For
ε>0 and
T∈L(H), let
rε(T) denote the
ε-pseudo spectral radius of
T. We characterize surjective maps
ϕ on
L(H) which satisfy
for all
T,S∈L(H). We also obtain analogous result for the finite-dimensional case, without the surjectivity assumption on
ϕ.