Cover - shares	6 Months Ended
	Jun. 30, 2021	Aug. 23, 2021
Cover [Abstract]
Entity Registrant Name	AeroCentury Corp
Entity Central Index Key	0001036848
Document Type	10-Q
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Small Business	true
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Document Period End Date	Jun. 30, 2021
Entity Filer Category	Non-accelerated Filer
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2021
Entity Common Stock Shares Outstanding		1,545,884
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-13387
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	94-3263974
Entity Address Address Line 1	1440 Chapin Avenue
Entity Address Address Line 2	Suite 310
Entity Address City Or Town	Burlingame
Entity Address State Or Province	CA
Entity Address Postal Zip Code	94010
City Area Code	650
Local Phone Number	340-1888
Security 12b Title	Common Stock
Trading Symbol	ACY
Security Exchange Name	NYSEAMER
Entity Interactive Data Current	Yes