  We propose a scenario where both inflation and dark matter are described by a
single axion-like particle (ALP) in a unified manner. In a class of the minimal
axion hilltop inflation, the effective masses at the maximum and mimimum of the
potential have equal magnitude but opposite sign, so that the ALP inflaton is
light both during inflation and in the true vacuum. After inflation, most of
the ALPs decay and evaporate into plasma through a coupling to photons, and the
remaining ones become dark matter. We find that the observed CMB and matter
power spectrum as well as the dark matter abundance point to an ALP of mass
$m_\phi = {\cal O}(0.01)$ eV and the axion-photon coupling $g_{\phi \gamma
\gamma} ={\cal O}(10^{-11})$GeV$^{-1}$: the ALP miracle. The suggested
parameter region is within the reach of the next generation axion helioscope,
IAXO. Furthermore, thermalized ALPs contribute to hot dark matter and its
abundance is given in terms of the effective number of extra neutrino species,
$\Delta N_{\rm eff} \simeq 0.03$, which can be tested by the future CMB
experiments. We also discuss a case with multiple ALPs, where the coupling to
photons can be enhanced in the early Universe by an order of magnitude or more,
which enlarges the parameter space for the ALP miracle. The heavy ALP plays a
role of the waterfall field in hybrid inflation, and reheats the Universe, and
it can be searched for in various experiments such as SHiP.
