An electric compressor includes a shaft with a forward leading groove and a reverse leading groove both engraved on its outer wall. When a motor rotates forward, the forward leading groove pumps up lubricant through a centrifugal pump thereby lubricating sliding sections of the compressor. The reverse leading groove has a lead directing opposite to that of the forward leading groove, and when the motor rotates reversely due to some reason, the reverse leading groove pumps up the lubricant through the centrifugal pump thereby lubricating the sliding sections.