I know there are various rules of thumbs such as 5-20 cases per variable in a scale or recommendations like Comrey and Lee's. Also it depends on communalities. But is there any solid way to justify that your sample size is adequate?
Ahmed, you could perform a Monte Carlo simulation study if you already have some knowledge about the population values to be expected.
Or, you may decide to read what other researchers think about this problem. Here is a great resource with several suggestions and references gathered by Nathan Zhao which may be helpful for you:
Most research and statistics books require the minimum sample size in EFA to be 5 -10 cases per each item in the scale. 100-200 cases should be "good enough" for 20-50 items.....but for all.....100 as poor, 200 as fair, 300 as good, 500 as very good