An object is to provide a wavelength tunable semiconductor laser device, a controller for the same and a control method for the same, which prevent wavelength drifts. The wavelength tunable semiconductor laser device includes an active region (2,3) for oscillating a laser beam, and a wavelength tuning region (4,11b) for shifting a wavelength of the laser beam. In this device, a thermal compensation region (4,11c) for converting most of the inputted electric power to heat is provided adjacent to the wavelength tuning region (4,11b), and the sum of an electric power inputted into the wavelength tuning region (4,11b) and an electric power inputted into the thermal compensation region (4,11c) is always kept constant.