We present the data release 14 Quasar catalog (DR14Q) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). This catalog includes all SDSS-IV/eBOSS objects that were spectroscopically targeted as quasar candidates and that are confirmed as quasars via a new automated procedure combined with a partial visual inspection of spectra, have luminosities Mi [z=2] < -20.5 (in a {LAMBDA} CDM cosmology with H_0_=70km/s/Mpc, {OMEGA}_M_=0.3, and {OMEGA}_{LAMBDA}_=0.7), and either display at least one emission line with a full width at half maximum larger than 500km/s or, if not, have interesting/complex absorption features. The catalog also includes previously spectroscopically-confirmed quasars from SDSS-I, II, and III. The catalog contains 526356 quasars (144046 are new discoveries since the beginning of SDSS-IV) detected over 9376 deg^2^ (2044 deg^2^ having new spectroscopic data available) with robust identification and redshift measured by a combination of principal component eigenspectra. The catalog is estimated to have about 0.5% contamination. Redshifts are provided for the MgII emission line. The catalog identifies 21877 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03mag. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3610-10140{AA} at a spectral resolution in the range 1300<R<2500, can be retrieved from the SDSS Science Archiver Server.