Animated movement problem

[Cosus]

Hello,
I'm trying to animate horizontal movement of simple object. I attached it under bone and the bone is just moving horizontaly. But that movement is not smooth, its jumping every few frames instead, what do I wrong?
Attached is motion graph screenshot with the curve as steps instead of line.
Thanks in advance.

[Víctor Paredes]

The default interpolation interval is set to 5 (you can see it in your screenshot, you have Linear and 5 as default values). That means that for every new keyframe you create, the objects will move every 5 frames.
To solve it, first set the default number to 1 (I'm assuming you want to animate in 1s).
Now, since your keyframes are already created, they won't be affected by this new default.
To fix the already created keys, just select them, then press right click over a key and set the interval to 1.