The term tsurugi (剣) designates a straight, double-edged, bladed weapon from Japan.

One of the most famous tsurugi is the one made in the Heian period (794－1185) owned by Kongō-ji and stored by Kyoto National Museum.

It is made to imitate the sword Fudo Myōō holds in his right hand, and the hilt is in the shape of a vajra, a Buddhist altar tool.

The most famous example is the legendary sword Kusanagi no Tsurugi which is one of the Three Imperial Regalia of Japan.

The tsurugi-tachi (剣太刀), a straight sword with only one side of the blade sharpened throughout, was similar to the tsurugi or ken.