My relevant keyword have a high first page bid? Please let me know why?

In your Pay-per-Click campaign, a quality score is shown for each keyword.Quality Score is used in several different ways, including influencing your keywords actual cost-per-clicks (CPCs) and estimating the first page bids that you see in your account. In general, the higher your Quality Score (out of 10),the lower your costs and the better your ad position.Quality Score ensures that Google only shows relevant ads to its users. Searchers want to find the information they are looking for quickly and easily and Quality Score helps Google show more relevant ads to the content on the URL that the ad drives them to. To make sure that your potential customers see your ad, you need to pay attention to Quality Score. It also influences your ads position, and it partially determines your keywords minimum bids, which can help reduce your budgets.