For the first time current quantization is reported for antimony sulfoiodide (SbSI) nanowires. It has been registered in current responses on electric field switching as well as on illumination on and off. Current steps determined in all experiments have been equal to each other within the experimental error. It has been explained by the quantized change of free carrier concentration in nanowire. Lateral dimensions of SbSI nanowires estimated from quantum steps are comparable with geometrical data reported for the same technology of material preparation.