PURPOSE: To provide a thread braking device capable of exhibiting less danger of damage to a thread and preventing the thread from being contaminated.

CONSTITUTION: A thread breaking device includes a pair of braking members 6, 6', which are arranged symmetrically with respect to a thread running path. The braking members 6, 6' respectively have spring members 7, 7'. Between these spring members 6, 6', a line-shaped and vertically-arranged braking zone is defined for a thread 18. For effecting a braking action, the spring members 7, 7' are pivoted by control arms 8, 8' toward the thread running path. Due to this movement of the spring members 7, 7' as well as due to the vertical arrangement thereof, deposition of contaminations in the braking zone is avoided. The elasticity of the spring members reduces danger of damage to the thread in the presence of thickened thread sections.