The suit was filed on Jan. 18 in the U.S. District Court in Delaware, Nidec said in a statement.
The Japanese component maker wants the court to award it appropriate compensation based on sales made by Seagate, a Nidec spokesman said.
At issue were spindle motor designs used to spin the HDD disk and the base plate the disk sits in, the spokesman said.
Seagate did not immediately respond to a request for comment.
Nidec has about 85% of the global market for HDD motors, which are used in computers and other devices including data centre equipment. Those motors account for around a tenth of the company's revenue.
(Reporting by Tim Kelly and Chang-Ran Kim; Editing by Leslie Adler and Stephen Coates)