A temperature-controlled semiconductor laser apparatus includes a semiconductor laser element, an optical fiber, a temperature controller, a thermistor, and a package. The semiconductor laser element emits a laser beam. The optical fiber receives the laser beam emitted from the semiconductor laser element. The temperature controller cools and heats the semiconductor laser element to keep the semiconductor element at a preset temperature. The thermistor detects an ambient temperature of the semiconductor laser element. The package accommodates at least the semiconductor laser element and the temperature controller in a sealed state and having the thermistor mounted on an inner wall of the package.