  The elliptic flow of electrons from heavy-flavour hadron decays at
mid-rapidity ($|y|$ $<$ 0.7) is measured in Pb-Pb collisions at $\sqrt{s_{\rm
NN}} = 2.76$ TeV with ALICE at the LHC. The particle azimuthal distribution
with respect to the reaction plane can be parametrized with a Fourier
expansion, where the second coefficient ($v_{\rm 2}$) represents the elliptic
flow. The $v_{\rm 2}$ coefficient of inclusive electrons is measured in three
centrality classes (0-10%, 10-20% and 20-40%) with the event plane and the
scalar product methods in the transverse momentum ($p_{\rm T}$) intervals
0.5-13 GeV/$c$ and 0.5-8 GeV/$c$, respectively. After subtracting the
background, mainly from photon conversions and Dalitz decays of neutral mesons,
a positive $v_{\rm 2}$ of electrons from heavy-flavour hadron decays is
observed in all centrality classes, with a maximum significance of $5.9\sigma$
in the interval $2 <$ $p_{\rm T}$ $<$ 2.5 GeV/$c$ in semi-central collisions
(20-40%). The value of $v_{\rm 2}$ decreases towards more central collisions at
low and intermediate $p_{\rm T}$ (0.5 $<$ $p_{\rm T}$ $<$ 3 GeV/$c$). The
$v_{\rm 2}$ of electrons from heavy-flavour hadron decays at mid-rapidity is
found to be similar to the one of muons from heavy-flavour hadron decays at
forward rapidity (2.5 $<$ $y$ $<$ 4). The results are described within
uncertainties by model calculations including substantial elastic interactions
of heavy quarks with an expanding strongly-interacting medium.
