Background: Although previous studies have measured attitudes about autism to understand ways to ameliorate stigmatized beliefs, nonautistic individuals' acceptance of autism is still not well understood. This study aimed to develop and pilot test the Autism Attitude Acceptance Scale (AAAS), a self-report instrument that measures nonautistic adults' autism acceptance based on the neurodiversity framework, and examine the associations between autism acceptance and purported variables (disability-related experience/awareness variables and demographic characteristics). Methods: The author piloted the AAAS with 122 nonautistic adults. Principal component analysis and reliability analysis were used to examine the factor structure and psychometric properties of the AAAS. The associations between the AAAS and autism knowledge, the quantity and quality of previous contact, neurodiversity awareness, and demographic variables were examined using Pearson's r correlations, t-tests, and analyses of variance. Results: The author constructed two subscales of the AAAS, General Acceptance (GA) and Attitudes toward Treating Autistic Behaviors (ATAB). The GA measures the acceptance of autism as a unique way of being, willingness to provide support to autistic individuals, and feeling comfortable while interacting with them. The ATAB measures how strongly a person believes that receiving treatments to reduce autistic symptoms will or will not benefit autistic individuals. The GA was associated with autism knowledge, quality and quantity of previous contact with autistic individuals, neurodiversity awareness, gender, ethnicity, and education level of participants. The ATAB was significantly associated with autism knowledge and quality and quantity of previous contact; the ATAB did not have any significant associations with neurodiversity awareness and demographic variables. Conclusions: The AAAS, which validly and reliably measures nonautistic individuals' autism acceptance, identified the subgroups with low autism acceptance. This study calls for further examination of the underlying mechanism of autism acceptance and neurodiversity framework to restructure nonautistic individuals' attitudes about autism.