The present invention relates to a wireless communication system and a mobile wireless communication apparatus. Both a pre-word (PW) and a sync word (SW) are used to establish a synchronization or only the sync word (SW) is used to establish a synchronization in accordance with an operational status related to the synchronization in a mobile wireless communication apparatus. For example, during an initial synchronization with a control channel (110) being received, both the pre-word (PW) and the sync word (SW) are used to establish a synchronization when a calculation result in a synchronization calculating part exceeds a predetermined threshold value only once. During an initial synchronization with a direct communication channel (112) being received, both the pre-word (PW) and the sync word (SW) are used to establish a synchronization when the calculation result exceeds the predetermined threshold value once; or alternatively, only the sync word (SW) is used to establish a synchronization when the calculation result successively exceeds the predetermined threshold value twice. According to the present invention, the sync word is shortened so as to quickly establish a communication link, and the sync detection can be performed with high precision.