There has been great concern about online business communication since the Covid-19 pandemic occurred. Salespeople using online tools have been facing difficulties conveying credibility to their customers, which is considered essential for business. Some studies have claimed that online tools allow one to change one's nonverbal cues in real-time; that is, many combinations of visual and audio cues can be applied that are not possible in face-to-face situations. This study was undertaken to clarify the effect of the combination of visual and audio cues on salesperson credibility in online tools. In this study, each male and female salesperson made a business presentation using Zoom with eight patterns of visual and audio combinations: three kinds of still images as visual (Name only /Profile photo with no expression/Profile photo with a smile) x two kinds of voices as audio (Dull/Bright) and two kinds of videos (with no facial expression and dull voice/ with facial expression and bright voice). Eight patterns of presentations by the male salesperson were watched by 55 participants, and the ones by the female salesperson were watched by 52 participants. Then, a questionnaire about salesperson credibility was conducted. As a result, Analysis of Variance (ANOVA) with the Tukey-Kramer test showed that salesperson credibility was affected by the combinations of visual and audio cues for both the male and female. Salesperson credibility consists of three factors: Trustworthiness, Competence, and Attraction. As for the male salesperson, audio cues affected credibility more than visual cues in most cases. Especially on the second factor, Competence, it was found that bright audio cues increased the salesperson's credibility, whichever visual cues were used. As for the female salesperson, not only audio cues but also visual cues affected her credibility. In particular, "Name x dull voice"significantly reduced her credibility.