Spirochetes have flagella within the cell body and swim by wriggling the spiral cell body. Besides they have been known to be critical agents causing various infectious diseases, their eccentric appearances and motilities have been attracting many scientists in a wide variety of fields other than bacteriologists. Unlike externally flagellated bacteria that swim by using flagella as a screw propeller, spirochetes progress in a liquid by changing their cell shapes. To understand the unique motion mechanism of spirochetes, many experiments and theoretical studies are being carried out. In this review, I will summarize morphological and motile properties of various species of spirochete, such as Borrelia, Treponema and Brachyspira. I will also expound on the motion mechanism of Leptospira with our latest results obtained by high-resolution optical photometry.