Ca12Al14O33 (Ca12Al7) phase nanophosphor material codoped with Er3+/Yb3+ ions has been synthesized through combustion route, and its UV/visible upconversion luminescence excited by infrared of 976 nm radiation has been monitored. Different batches of samples were calcinated in air at different temperatures, and then changes in the upconversion luminescence have been studied. Freshly synthesized sample shows low upconversion efficiency; however the sample calcinated at 1473 K shows a bright upconverted emission. The Yb3+ and Yb2+ ionic states of Yb have been observed in the samples, and the enhancement in upconversion intensities has been attributed to the conversion of Yb2+ and Yb3+. The upconversion emissions from Er3+ ions have been observed at 335, 366, 380, 408, 475, 523, 548, 661, and 848 nm wavelengths and have been assigned to the transitions 4G9/2→4I13/2, 2G9/2→4I15/2, 4G11/2→4I15/2, 2P3/2→4I13/2(2H9/2→4I15/2), 4F3/2→4I15/2, 2H11/2→4I15/2, 4S3/2→4I15/2, 4F9/2→4I15/2, and 4I9/2→4I15/2, respectively. The bands at 408, 523, 548, and 661 nm are very intense and can be detected even with the eye using suitable filters at pump power of as low as 50 mW. The pump power dependence of the emission intensities for different bands has been investigated and shows a strange behavior.