A read reclaim method of a storage device includes detecting, at a cycle of a random number of read operations, the number of error bits within non-selection data stored in each of a plurality of memory blocks. A memory block having the number of detected error bits, with respect to the number of read operations, increasing at a rate greater than a reference rate over one or more cycles of the random number of read operations is selected as a weak block. The number of error bits within non-selection data stored in the weak block is detected at a cycle of a fixed number of read operations. A detection is made of whether the number of error bits detected according to the fixed-number cycle is greater than or equal to a read reclaim reference. The non-selection data is data not requested by a host.