PURPOSE: To provide a deinking agent excellent in deinking and foreign substance-removing ability and capable of improving paper physical properties, containing a basophilic cellulase with a non-destructive index at a specific value or higher.

CONSTITUTION: This deinking agent contains a basophilic: cellulase selected from a group composed of alkali cellulase K, alkali cellulase K-534, alkali cellulase K-539, alkali cellulase K-577, alkali cellulase K-521, alkali cellulase K-580, alkali cellulase K-588, alkali cellulase K-597, alkali cellulase K-522, CIVIC ase I, CMC ase-II, alkali cellulase E-II and alkali cellulase E-III. The basophilic cellulase has the following characteristics: non-destructive index expressed by the formula: 2500; optimum pH with CMC as substrate: ≥7; and relative activity at ≥pH8: ≥50% of that under the optimum conditions. A deinking process is as follows: this deinking agent is made to act on waste paper stock such as newspaper at an oxygen activity of ≥50 units with CMC as substrate.