Patent ID: 8120953

Claim:
A reading method of a nonvolatile semiconductor memory device, the method comprising: supplying, to a word line, one of a voltage corresponding to a highest reading level or a voltage having a level higher than a first reading level of a read operation to be performed on the word line; subsequently supplying a voltage of the first reading level to the word line and performing the read operation; subsequently supplying a voltage of the second reading level to the word line, wherein supplying the voltage of the second reading level is continued during a first sensing period of the read operation; supplying, to the word line, a fourth voltage having a level higher than a third reading level of the read operation to be performed on the word line; and subsequently supplying a voltage of the third reading level to the word line, wherein supplying the voltage of the third reading level is continued during a third sensing period of the read operation, wherein the voltage having a level higher than the first reading level of a read operation corresponds to a voltage of a second reading level of the read operation, the voltage of the second reading level being higher than the voltage of the first reading level, and the third voltage corresponds to a voltage of a third reading level of the read operation, the voltage of the third reading operation being higher than the voltage of the second reading level.