  We investigated the possibility of acceleration of ultra-high-energy cosmic
rays (UHECRs) in nearby active galactic nuclei (AGNs) using archival
multi-wavelength observational data, and then we constrained their physical
conditions, i.e., the luminosity of the synchrotron radiation and the size of
the acceleration site. First, we investigated the spatial correlation between
the arrival directions of UHECRs and the positions of nearby AGNs in the Fermi
third gamma-ray source catalog. We selected 27 AGNs as candidates of
accelerators of UHECRs. Then, we evaluated the physical conditions in the
acceleration regions of these AGNs via the Pe'er and Loeb method, which uses
the peak luminosity of synchrotron radiation and the peak flux ratio of inverse
Compton scattering to synchrotron radiation. From the evaluation, we found that
six AGNs have the ability to accelerate ultra-high-energy protons in the AGN
cores. Furthermore, we found that the minimum acceleration size must be more
than a few kpc for acceleration of UHE protons in the AGN lobes.
