Objectives This study aimed to develop and test a questionnaire's validity and reliability to evaluate undergraduate dental students' feelings regarding child dental care. Methods The questionnaire was developed using a focus group of 10 undergraduate dental students. This questionnaire was then structured and applied digitally via Google Forms to 90 dental students aged 22.95 years (±0.89) who had already completed or were enrolled in a pediatric dentistry discipline. The test–retest was conducted with 15 students. Descriptive analysis, exploratory factorial analysis (EFA), and intraclass correlation coefficient were performed to evaluate the test–retest reliability, Cronbach's alpha (α) to measure the internal consistency, and Mann–Whitney test was used to determine the discriminant validity (p < 0.05). Results The final version of the questionnaire concerning the feelings of dental students when faced with pediatric dental treatment comprised three items, which evaluated anxiety, fear, and insecurity. The visual analog scale was used to evaluate the answer for each item. The questionnaire resulted in a total score that varied from 0 to 10. The higher the score on the questionnaire, the greater the negative feelings regarding pediatric dental treatment. The results of the EFA were satisfactory (Bartlett's sphericity = 0.001; Kayser–Meyer–Olkin measure = 0.725). The EFA extracted a single dimension with an eigenvalue of 2.4 and a total explained variance of 80%. The internal consistency of the questionnaire was satisfactory (α = 0.877), and the test–retest reliability was good (intraclass correlation coefficient = 0.691). Students who felt confident about carrying out invasive procedures in children demonstrated more positive feelings related to the pediatric dental treatment (average = 3.50 ± 2.73) than those who did not feel such confidence (average = 5.00 ± 2.35; p = 0.007). Conclusions The unidimensional questionnaire proposed by this study is valid and reliable in evaluating the feelings of undergraduate dental students regarding child dental care.