Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2019
Feb. 12, 2020
Jun. 28, 2019
Cover [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2019    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Trading Symbol MNOV    
Entity Registrant Name MEDICINOVA INC    
Entity Central Index Key 0001226616    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Common Stock, Shares Outstanding   43,956,020  
Entity Public Float     $ 392,964,130
Entity File Number 001-33185    
Entity Tax Identification Number 33-0927979    
Entity Address, Address Line One 4275 Executive Square    
Entity Address, Address Line Two Suite 300    
Entity Address, City or Town La Jolla    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 92037    
City Area Code 858    
Local Phone Number 373-1500    
Document Annual Report true    
Document Transition Report false    
Entity Incorporation, State or Country Code DE    
Entity Interactive Data Current Yes    
Title of 12(b) Security Common Stock, par value $0.001 per share    
Security Exchange Name NASDAQ    
Documents Incorporated by Reference

Portions of the registrant’s Proxy Statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A in connection with the registrant’s 2020 Annual Meeting of Stockholders, which will be filed subsequent to the date hereof, are incorporated by reference into Part III of this Form 10-K.