On UT June 2 2013, we use the Double Spectrograph mounted on the 200-inch Hale telescope at Palomar Observatory to spectroscopically follow up a recent M31 nova candidate, M31N 2013-05b (ATel #5092 and #5099). Its spectrum shows very weak continuum superposed by strong Halpha emission with FWHM of about 1200 km/s. The peak flux density of Halpha is at 6560 Angstrom, roughly consistent with the velocity of M31. Therefore, this spectrum confirms that M31N 2013-05b is a nova in M31.
