When I first got my Nikon D40, and was dismayed to find that my first few "test photo" contained a couple of dust marks just like your's.
Because it was my first proper DSLR camera, I had thought about taking it back to where I bought it from and buy a high-end bridge camera instead but having done a bit of research on the interweb about dustspots on DSLR camera, I popped into my local independent camera shop and bought a pack of 3 wet/dry swabs which costed me £13.
I then set the camera to lock the mirror up and held my breath as I carefully lowered the wet swab onto the sensor and then the dry one . . . and it really worked! Result: one totally dustfree camera.
However, since my other camera, a Fuji S5600, is quite capable of taking brilliant pictures at 10 x zoom (well, at least I think so anyway!), I won't need to change the lens on my Nikon D40 in order to take zooms, this way it minimises the risk of any more dust getting into the mirror chamber (or whatever it's called!). I'm quite happy with the supplied 18 - 50 mm lens it came with! I'm glad I thought about using these swabs as I went onto loving this camera to bits.