The aim of this study is to obtain the new historical knowledge on the illegalities of animal fighting based on the statutes in 19th-century Britain, through the analysis of the historical relations between 'The Cruelty to Animals Act 1835' and the preceded laws. The obtained result is as follows. Animal fighting had received intervention by justices of the peace, also before enacting the 1835 Act, but as a result of it being shown clearly by the King's Bench's determination that 1822 Act could not be applied to animal fighting including bull-baiting, those who were going to prosecute persons committing animal fighting could not but depend on the common law. But, it was difficult to apply 'nuisances' to all cases of animal fighting. However, the Parliamentary trend to animal fighting has changed since 1830s. The Bill 1832 has an aim to specify the illegality of animal fighting clearly since the beginning. Although the 1832 bill was not passed, it drew out the investigation by the Select Committee in the House of Commons, and the report pointed out the defect of the current law about the regulation of animal fighting. The s.29 in 'Police magistrates, Metropolis Act 1833' accepted the illegality of animal fighting in the Metropolis from the based view of the demoralization of the people. And, this regulation was added to the 1833 bill hurriedly by the proposal of Joseph Pease MP and Hon. George Lamb MP in the House of Commons. The 1835 Bill moved by Mr. Pease has contained 'cruelty to animals', 'annoyances', 'nuisances', 'demoralizations' as the basics relating to the illegalities of animal fighting in s.ll. We should recognize that as the influence of the result in the indication on the illegalities of animal fighting in the Report by the Select Committee in 1832 and the 1833 Act, s.29. So, it comes to conclusions, that the 1835 Act added the three basics relating to the illegalities of animal fighting 'cruelty to animals', 'annoyances', and 'nuisances' to 'demoralizations' in the 1833 Act s.29. However, 'nuisance' is a charge in the common law. Therefore, a historical meaning of 1835 Act is to specify clearly the illegalities relating to animal fighting shown by the statute, instead of by the common law till then. Moreover, the British Parliament resulted in presenting the legal conditions for legalizing animal sports through the 1835 Act. It was to wipe away the four above-mentioned basics of the illegalities from it, and to reckon with the animal welfare.