To provide a public telephone which can make effective advertisements without disturbing speech and, accordingly, enables users to make speech free of charge or at low charges, and a line connecting method of such public telephone.

When the hook switch 92 of the public telephone is not turned on, namely, when the receiver 20 of the telephone is not connected to the telephone line, a CPU 81 reads out the image data corresponding to a guidance image informing that the public telephone is a free-of-charge telephone from a storage device 84 and causes a main display device 40 to display the image through a display driving section 82. When the hook switch 92 is turned on, namely, when the receiver 20 is connected to the telephone line, the CPU 81 reads out image data for advertisement from the storage device 84 and causes the display device 40 to display an advertising image instead of the guidance image through the driving section 82.