This paper describes a method for location-estimation of mobile wireless LAN clients using strength of received signals from wireless LAN access points that are settled at various places in the multistoried buildings. A lot of training data that pertains between location of wireless LAN client and strength of received signals from wireless LAN access points at the location are needed to construct the location estimation system. We focus on the simplified measurement that the time interval for acquisition of strength of signals is shorter. We examine the location estimation under the condition that the measurement interval for strength of received signals for validation data is shorter; the interval is supposed to the real application. Experimental results show the feasibility of the short measurement interval for data acquisition.