We present a large sample of Ly{alpha}-emitting galaxies (LAEs) spectroscopically confirmed at redshift z~4.5, based on Inamori-Magellan Areal Camera and Spectrograph spectroscopic observations of candidate z~4.5 Ly{alpha}-emitting galaxies in the large area Lyman alpha (LALA) narrowband imaging survey Cetus field. We identify 110 of them as z~4.5 Ly{alpha} emitters based on single-line detections with no continuum emission blueward of the line. Six foreground galaxies are identified, either based on multiple lines or blueward continuum emission. The Ly{alpha} confirmation rate varies from <50% to 76% for candidates selected in different narrowband filters at slightly different redshifts. The sample includes many objects with equivalent widths (EWs)>~200{AA}. These large EW candidates are spectroscopically confirmed at the same rate as candidates with more modest EWs.