A blade sharpener including a main frame casing having a grip and a grinding chamber and a grinder assembly detachably installed in the grinding chamber in which the grinder assembly is formed by a pair of shaft supports facing each other, a supporting window provided in each of the shaft supports, a rotary shaft supported at both end portions thereof by the vertical shaft supports, an abrasive wheel provided on the rotary shaft at substantially its axial center, and a pair of lateral coil springs each provided on either side of the abrasive wheel. The rotary shaft can be supported by a pair of longitudinal coil springs installed in the shaft supports.