To provide a waste foamed rubber recycling method capable of reducing the volume of a large amount of waste foamed rubber and devulcanizing it by using a twin-screw extruder.

When the waste foamed rubber to be treated is supplied to the supply part on the upstream side of the twin-screw extruder consisting of a cylinder barrel (1) and the screws (20 and 20') rotationally driven in the cylinder barrel to be kneaded and melted while successively transported in a downstream direction and the kneaded rubber is discharged from the downstream end of the barrel while the gas generated at the time of kneading is removed to obtain a reutilizable raw material, the waste foamed rubber is weakly kneaded (K1) on the downstream side of the supply part (2) while discharging the air generated by weak kneading and the weakly kneaded rubber is kneaded and melted (K2) on the downstream side of (K1) while discharging the gas generated by this kneading and melting. Further, the kneaded rubber is kneaded and melted (K3) on the downstream side of (K2) and the gas generated by this kneading and melting is forcibly degassed by a negative pressure source (9) to obtain the reutilizable raw material.