To provide a torque detection device capable of detecting a torque with stable accuracy.

This torque detection device has a drive shaft 4 rotating by receiving the drive of a motor 3, and an output shaft 7 connected to the drive shaft 4 through a torsionally-deformable coil spring 6. The device also has a casing 2 for specifying the connection length of the drive shaft 4, the coil spring 6 and the output shaft 7 to be constant, and pulse encoders 5, 8 for emitting pulse signals corresponding to the rotation of the drive shaft 4 and the output shaft 7 respectively. The device has a constitution wherein the pulse signals of the pulse encoders 5, 8 are processed by an operation means 9, to thereby determine the rotation angle difference between the drive shaft 4 and the output shaft 7, and a load torque loaded on the output shaft 7 is calculated therefrom.