A machine for treating organic waste, comprising: a casing defining an inner treatment chamber delimited at least in part by a sieving grid, and an inlet aperture for inserting waste at an end of the chamber and an outlet aperture for discharging at an opposite end in respect to the inlet aperture; at least a shaft installed in said inner chamber, equipped with mechanical means for grinding or pressing the inserted organic waste against the sieving grid or against at least a wall that delimits the inner treatment chamber; a first motor, functionally coupled to said shaft; a first transmission system configured to transmit to said shaft a rotation motion of the shaft along a longitudinal axis, generated by said first motor; a first protection sensor, configured to sense a blockage condition of a rigid object that hinders rotation of the shaft and to generate a related alarm signal when said blockage condition is detected; a control unit functionally coupled to said first protection sensor and to the first motor and configured for stopping a run of the first motor when said alarm signal is generated; characterized in that said first transmission system comprises a first driving pulley connected to the motor, a second idle pulley connected with the shaft, and a friction transmission belt tightened between the first driving pulley and the second idle pulley, said belt being configured to slip against said pulleys (9, 10) when a torque exceeding a nominal maximum value for rotating said shaft is requested; said first protection sensor is configured to sense a slippage of said friction transmission belt and to generate the alarm signal when said slippage is detected. a casing defining an inner treatment chamber delimited at least in part by a sieving grid, and an inlet aperture for inserting waste at an end of the chamber and an outlet aperture for discharging at an opposite end in respect to the inlet aperture; at least a shaft installed in said inner chamber, equipped with mechanical means for grinding or pressing the inserted organic waste against the sieving grid or against at least a wall that delimits the inner treatment chamber; a first motor, functionally coupled to said shaft; a first transmission system configured to transmit to said shaft a rotation motion of the shaft along a longitudinal axis, generated by said first motor; a first protection sensor, configured to sense a blockage condition of a rigid object that hinders rotation of the shaft and to generate a related alarm signal when said blockage condition is detected; a control unit functionally coupled to said first protection sensor and to the first motor and configured for stopping a run of the first motor when said alarm signal is generated; characterized in that said first transmission system comprises a first driving pulley connected to the motor, a second idle pulley connected with the shaft, and a friction transmission belt tightened between the first driving pulley and the second idle pulley, said belt being configured to slip against said pulleys (9, 10) when a torque exceeding a nominal maximum value for rotating said shaft is requested; said first protection sensor is configured to sense a slippage of said friction transmission belt and to generate the alarm signal when said slippage is detected.