Cross-ventilation is regarded to be beneficial control method to obtain thermal comfort in a hot summer without using mechanical devices. Since it is complicated flow phenomenon, details of flow characteristics have not been sufficiently known. The final goal of this work is to establish a new prediction method of flow rate based on energy balance within the stream tube passing through or around the building. To validate numerical results obtained by CFD, they need to be compared with experimental results. This paper presents wind tunnel measurement of flow characteristics inside and outside a cross-ventilated model. Velocity and pressure were measured along the central line of the stream tube for internal flow, and velocity distribution of the external flow was measured by Particle Image Velocimetry (PIV).