An information recording/reproducing device includes a recording layer, and a recording circuit which records data to the recording layer by generating a phase change in the recording layer. The recording layer includes a first chemical compound having a spinel structure. The recording layer is AxMyX4 (0.1≦x≦2.2, 1.0≦y≦2.0), where A includes one selected from a group of Zn, Cd and Hg, M includes one selected from a group of Cr, Mo, W, Mn and Re, and X includes O.