(Amended) A shifting mechanism of a vehicular manual transmission having a highest "n"th-speed position and configured to perform a shift-down action from said "n"th-speed position to an "n-1"th-speed position upon a diagonal shifting operation of a manual shift lever, the shifting mechanism comprising: a selector lever operatively connected to said manual shift lever and operable to at least two selecting positions; a shifter lever operatively connected to said manual shift lever and operable to a neutral position and two operating positions on respective opposite sides of the neutral position; a plurality of shifter fork shafts (14, 16, 18) each of which is provided with an integrally formed shifter fork (24, 26, 28) and an integrally formed shifter head (40, 44, 48), said shifter fork shafts being disposed so as to extend in parallel with a shifter/selector shaft such that the shifter fork shafts are axially movable and such that the shifter heads of the shifter fork shafts are located along an arc about an axis of said shifter/selector shaft; an inner lever fixed to said shifter/selector shaft and movable in an axial direction of the shifter/selector shaft, in synchronization of a shifting operation of said shifter lever, to axially move said shifter fork shafts; and an interlocking member supported by said shifter/selector shaft such that the interlocking member is axially movable and rotatable relative to the shifter/selector shaft, said interlocking member being pivoted in synchronization with an operation of said selector lever to a selected one of the selecting positions, to pivot said inner lever to a selected angular position at which the inner lever is held in engagement with the shifter head of a selected one of said plurality of shifter fork shafts, said interlocking member permitting said inner lever to be moved in the axial direction of the shifter/selector shaft and being configured to lock each of the shifter heads not in engagement with said inner lever, at a neutral position thereof; said shifting mechanism being characterized in that: the shifter head of one of the shifter fork shafts (14, 16, 18) which is to be moved by said inner lever to select said "n"th-speed position of said manual transmission at one of the selecting positions of said selector lever which corresponds to the "n"th-speed position, partially overlaps said interlocking member in a direction of pivoting of the interlocking member. a selector lever operatively connected to said manual shift lever and operable to at least two selecting positions; a shifter lever operatively connected to said manual shift lever and operable to a neutral position and two operating positions on respective opposite sides of the neutral position; a plurality of shifter fork shafts (14, 16, 18) each of which is provided with an integrally formed shifter fork (24, 26, 28) and an integrally formed shifter head (40, 44, 48), said shifter fork shafts being disposed so as to extend in parallel with a shifter/selector shaft such that the shifter fork shafts are axially movable and such that the shifter heads of the shifter fork shafts are located along an arc about an axis of said shifter/selector shaft; an inner lever fixed to said shifter/selector shaft and movable in an axial direction of the shifter/selector shaft, in synchronization of a shifting operation of said shifter lever, to axially move said shifter fork shafts; and an interlocking member supported by said shifter/selector shaft such that the interlocking member is axially movable and rotatable relative to the shifter/selector shaft, said interlocking member being pivoted in synchronization with an operation of said selector lever to a selected one of the selecting positions, to pivot said inner lever to a selected angular position at which the inner lever is held in engagement with the shifter head of a selected one of said plurality of shifter fork shafts, said interlocking member permitting said inner lever to be moved in the axial direction of the shifter/selector shaft and being configured to lock each of the shifter heads not in engagement with said inner lever, at a neutral position thereof; the shifter head of one of the shifter fork shafts (14, 16, 18) which is to be moved by said inner lever to select said "n"th-speed position of said manual transmission at one of the selecting positions of said selector lever which corresponds to the "n"th-speed position, partially overlaps said interlocking member in a direction of pivoting of the interlocking member.