An electrode post connection structure for connecting a connection conductor to an electrode post of a battery through a connection fitting, which includes a lock stage portion formed on a circumference of the electrode post, a tapered portion formed at a top portion of the electrode post, a lock spring inserted in the connection fitting so as to engage with the lock stage portion to thereby lock the electrode post and the connection fitting with each other, and a hollow elastic body accommodated in the connection fitting so as to press the connection conductor to thereby connect the electrode post and the connection conductor to each other. Thus, work for connecting a connection conductor to an electrode post of a battery is simplified, and the electric characteristic and reliability of the connection are improved greatly.