A semiconductor storage device includes a bit line driver, and a control circuit configured to be able to execute a writing sequence for repeating at least one loop including a program operation for writing data into at least one of the plurality of memory cells and a verify operation for verifying the data a plurality of times while increasing a program voltage by a step-up voltage. The bit line driver can obtain a number of memory cells into which writing is completed or a number of memory cells into which writing is insufficient for each of the at least two consecutive loops from a result of the verify operation, and the control circuit can determine the step-up voltage in the subsequent loop based on a result obtained by the bit line driver.