| Document and Entity Information | Sep. 07, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Sep. 7, 2021 |
| Entity Registrant Name | BLACK SPADE ACQUISITION CO |
| Entity Incorporation, State or Country Code | E9 |
| Entity File Number | 001-40616 |
| Entity Tax Identification Number | 00-0000000 |
| Entity Address, Address Line One | Suite 2902, 29/F, The Centrium |
| Entity Address, Address Line Two | 60 Wyndham Street |
| Entity Address, City or Town | Central |
| Entity Address, Country | HK |
| Entity Address, Postal Zip Code | 00000 |
| Country Region | 852 |
| City Area Code | 3955 |
| Local Phone Number | 1316 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001851908 |
| Common Class A [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Class A ordinary shares, $0.0001 par value, included as part of the units |
| Trading Symbol | BSAQ |
| Security Exchange Name | NYSE |
| Redeemable Warrants [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Redeemable warrants, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50, included as part of the units |
| Trading Symbol | BSAQWS |
| Security Exchange Name | NYSE |
| Units [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Units, each consisting of one Class A ordinary share and one-half of one redeemable warrant |
| Trading Symbol | BSAQU |
| Security Exchange Name | NYSE |
