To provide a detent structure for a vehicular automatic transmission suitable for making effective use of a space in the body of a transmission case and improving the assembling efficiency of parts to be stored in the transmission.

The detent structure 1 for the vehicular automatic transmission comprises a manual plate 4 to be turned in response to the range position change-over operation of a control lever by a driver and having a plurality of cam grooves 4a on the outer periphery and a detent spring 6 for elastically energizing an engaging portion 6a toward the plate 4 to engage with the cam groove 4a corresponding to the turning position of the plate 4 out of the plurality of cam grooves 4a with the turning of the plate 4. With the engagement of the engaging portion 6a with the cam groove 4a, a range position is held as selected by the range position change-over operation. The detent spring 6 is seated and fixed onto a mating face 3a of the outer face of the body 3 of the transmission case 2 where a side cover 7 is mounted, and the engaging portion 6a is inserted into the body 3.