Synthetic cannabinoids (SCs) are one of most abused new psychoactive substances. While Cannabinoid receptor 1 (CB1) agonistic effects of natural cannabinoids are well understood, data related to novel SCs remains limited. In this study, we aimed to evaluate the CB1 agonistic effects of a total of 16 drugs, including a newly synthesized SCs in in vitro and in vivo. We also investigated to determine whether the results exhibited a direct correlation. For in vitro assay, Ca²⁺ assay was performed using CB1-Gα15 stable expressed cell line. The potency and efficacy of SCs was calculate as EC₅₀ and E_max in comparison with those of JWH-018. 5F-MDMB-P7AICA and CUMYL-like showed higher or similar effects. MDA -like and LY-2183240 were considered to have a relatively weak CB1 agonistic effects. Consistent with the in vitro findings, catalepsy was strongly induced by 5F-MDMB-P7AICA and CUMYL-like drugs in in vivo study. To ascertain the existence of a correlation among these results, we executed Spearman rank correlation analysis. Reflecting on the rank of intensity of catalepsy induction, a very strong correlation was observed in EC₅₀ (rank), accompanied by a strong correlation in E_max (rank) values. These results suggest that our in vitro model for assessing CB1 agonistic effects is appropriate for determining the potency and efficacy of SCs and serves as a reliable metric for evaluating newly synthesized SCs.