To provide a charging device that charges a battery in a portable terminal, which incorporates the battery therein and is an object to be charged, and adjusts the output voltage to an output voltage which is more suitable for the type of the portable terminal to be charged.

In a switching circuit 120 provided in a charging device 100, the on-off states of switching elements M1, M2 are set based on the states of voltage application from the exterior of the charging device to connection terminals T3, T4. A voltage signal is generated according to the set on-off states and is provided to a control circuit 110 (output voltage control means). Then, the control circuit 110 controls an output voltage applied from an output terminal T1 to a portable terminal 1 on the basis of the obtained voltage signal.