回複：lease上沒有寫需要提早幾天通知租客不續約. 回複：回複：煤氣斷氣，請問如何應對租客 （更新）

I thought you were in Chicago.  I might be wrong, but always check your local law.  It doesn't hurt to notify the tenant early.

http://www.illinoislegaladvocate.org/index.cfm?fuseaction=home.dsp_content&contentID=5397

No notice of termination of tenancy is required at the expiration of the lease period.  735 ILCS 5 / 9-213. However, if the Chicago ordinance (CRLTO) governs the rental agreement, the landlord must notify the tenant in writing at least 30 days prior to the date of termination of the lease or the landlord's intention not to renew the lease.  Section 5-12-130(j);