A mobile phone, when it is stolen or lost, autonomously detecting and protecting by itself the data held inside, wherein a security managing unit performs a predetermined security operation based on the above detection results wherein when it judges there is "no user presence reaction" by a user presence monitoring unit and it judges the power is on by a power monitoring unit or when it judges that the power is being turned off and the power is turned back on, it locks the access to data, evacuates the data outside, or deletes the data in accordance with the results of judgment whether the phone is in range or out of range by a radio status monitoring unit.