To provide a novel opening/closing structure for a flip provided to a portable phone, which is superior in evaluation on the market, a flip (3) that is rotatable in an opening direction from a condition where a phone operating portion (2) provided on a surface of a portable phone body (1) is covered by the flip to the condition where the phone operating portion (2) is exposed is provided at a predetermined position on the surface of the portable phone body (1). A biasing mechanism is provided with a closing biasing force to bias the flip (3) in a closing direction in a closed side position from a predetermined position B in the case where the flip (3) kept under the condition where the phone operating portion (2) is covered is rotated through a predetermined distance when the flip (3) is kept slanted to the surface of the portable phone body (1) and an opening biasing force to bias the flip (3) in an opening direction in an opened side position from the predetermined position B is provided in a hinge portion (4) between the flip (3) and the portable phone body (1).