if he is scratching his ears occasionally, like a couple times a day, that's completely normal. If he is continually scratching it or acts like it itches (rear leg comes up) when you clean it, then I would say probably ear mites, however, ear mites usually create a black waxy/bloody substance in the ear. So if you aren't seeing that it's either a slight case of mites, or just normal scratching

 

Cats can also get fungal (yeast) infections or bacterial infections in their ears, so if you notice a lot of scratching or head shaking, it could be that too. Occasional scratching is normal, but if it is persistent or he's acting like his ears bother him, a vet visit is probably in order.
The cats that I've seen with ear problems often look like they're trying to dig in their ear with their hind paw. They may have their head tilted after scratching at it or hold their ear at a funny angle. Or they do a funny head tilt and then start scratching at it.

 

Thanks for responding, at least there is two person saying its normal to scratch occasionally, maybe most cats don't scratch. The ear wax thing is not so severe this time as compared to the time in Jan when I brought him to the vet. I thought it was ear mite, but vet says otherwise by just merely looking into ET's ear with her naked eye and prescribed ear drop. This time round, the wax is also black and not bloody, and not as bad as in Jan. His ear isn't sore.

Yes Nell, he actually used his hind leg to dig his right ear. I did try to smell his ear, to find out if there is any odor...nothing, no smell, not sore. I'm still not sure if his scratching is considered occasional or frequent enough to warrant a visit to the vet, but at least if I know occassional scratching is normal, then I will have to monitor how often he scratch. Of course, the very excessive scratching behaviour I have noticed so far, is when he was on chicken. Ok, maybe I am abit paranoid cos for a long period when he was off chicken, I don't see that much scratching or maybe I haven't even noticed he was actually scratching all along? Oh well, ET is my 1st cat, haven't seen and know enough to be sure.

 

my cat does this too. i got kinda worried reading your post, but then I remembered I took my cat to the vet 3 weeks ago (and Keeb has been doing this since I've had him), and the vet checked his ears and said everything is fine.

I find that sometimes when he tries to 'dig into his ear' as you put it there's just some earwax built up in there, and I'll just clean it out with my finger. Then he seems to stop the scratching.

 

When the ear wax was bad in Jan, Vet even said it was ok, and your vet said your kitty is ok, so I can safely assume that occasional ear wax isn't much of an issue.

I cleaned ET's ear, and yet he is still digging his ear and shake his head vigorously enough that I hear a sound from him - its like a flapping sound from his lips? lol. Since yesterday, I have seen him shake his head only once, its probably something like once or twice a day, if I'm not wrong. I still need to monitor how often his scratches and digs his ear.

 

Both my cats scratch themselves occasionally (like a couple times a day), and I think that's pretty normal. Just about every mammal seems to get random little itchies from time to time.

But if it seems excessive, I would take him to the vet.