A driving end of a tool comprising: a body (10, 10a) including a chamber (11, 11 a), with the chamber (11, 11 a) defining first and second sectional areas (111, 112, 111 a, 112a); a first engaging member rotatably disposed in the first sectional area (111, 111a) and including two different ends defining a first engaging section and a second engaging section respectively, with the first engaging section extending circumferentially on an outer periphery of the first engaging member and including a plurality of teeth, with the second engaging section engaging with an object to be driven by the driving end of the tool; a second engaging member rotatably disposed in the second sectional area (112, 112a) and including two different ends defining first and second engaging ends (31, 32) respectively, with the first engaging section engaged with the first engaging end, with the first engaging end extending circumferentially on an outer periphery of a first end of the second engaging member and including a plurality of teeth, with the second engaging end extending circumferentially on an outer periphery of a second end of the second engaging member and including a plurality of teeth; at least one pawl (40, 40a) slidably disposed in the second sectional area and defining a first engaging portion (41, 41 a) including a plurality of teeth, with the second engaging end selectively engaged with the first engaging portion (41, 41a); and a switch (50, 50a) pivotally engaged with the body (10, 10a) and abutted against the at least one pawl (40, 40a); and wherein a pitch between two adjacent teeth of the first engaging section and a pitch between two adjacent teeth of the first engaging end are substantially the same, wherein a pitch between two adjacent teeth of the second engaging end is relatively smaller than that of the first engaging end, and wherein a pitch between two adjacent teeth of the first engaging portion is substantially the same as that of the second engaging end. a body (10, 10a) including a chamber (11, 11 a), with the chamber (11, 11 a) defining first and second sectional areas (111, 112, 111 a, 112a); a first engaging member rotatably disposed in the first sectional area (111, 111a) and including two different ends defining a first engaging section and a second engaging section respectively, with the first engaging section extending circumferentially on an outer periphery of the first engaging member and including a plurality of teeth, with the second engaging section engaging with an object to be driven by the driving end of the tool; a second engaging member rotatably disposed in the second sectional area (112, 112a) and including two different ends defining first and second engaging ends (31, 32) respectively, with the first engaging section engaged with the first engaging end, with the first engaging end extending circumferentially on an outer periphery of a first end of the second engaging member and including a plurality of teeth, with the second engaging end extending circumferentially on an outer periphery of a second end of the second engaging member and including a plurality of teeth; at least one pawl (40, 40a) slidably disposed in the second sectional area and defining a first engaging portion (41, 41 a) including a plurality of teeth, with the second engaging end selectively engaged with the first engaging portion (41, 41a); and a switch (50, 50a) pivotally engaged with the body (10, 10a) and abutted against the at least one pawl (40, 40a); and wherein a pitch between two adjacent teeth of the first engaging section and a pitch between two adjacent teeth of the first engaging end are substantially the same, wherein a pitch between two adjacent teeth of the second engaging end is relatively smaller than that of the first engaging end, and wherein a pitch between two adjacent teeth of the first engaging portion is substantially the same as that of the second engaging end.