A temperature detection apparatus and a rotation angle detection apparatus are provided that allow a temperature of a resolver to be calculated in real time. A rotation angle detection apparatus (10) (temperature detection apparatus) includes a resolver (20) with an excitation coil and output coils wound thereon, the excitation coil being subjected to an excitation voltage (VA) and the output coil outputting voltage signals (VB, VC) corresponding to the excitation voltage (VA), and a temperature calculation circuit (sensor microcomputer (32)) that detects a phase of the excitation voltage (VA) and that detects a phase of an excitation current (IA). The temperature calculation circuit (sensor microcomputer (32)) calculates a temperature of the resolver (20) based on a phase difference between the excitation voltage (VA) and the excitation current (IA).