Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 16, 2021
Document Information Line Items
Entity Registrant Name	Biotech Acquisition Co
Trading Symbol	BIOT
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Central Index Key	0001825413
Entity Current Reporting Status	No
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	true
Entity Ex Transition Period	false
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-39935
Entity Incorporation, State or Country Code	E9
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	545 West 25th Street
Entity Address, Address Line Two	20th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10001
City Area Code	(212)
Local Phone Number	227-1905
Title of 12(b) Security	Class A ordinary shares included as part of the units
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Class A Ordinary Shares
Document Information Line Items
Entity Common Stock, Shares Outstanding		23,000,000
Class B Ordinary Shares
Document Information Line Items
Entity Common Stock, Shares Outstanding		5,750,000