The aim of this present study is to ratify the scale of behavioural biases such as overconfidence, herding effect, loss aversion and investment decisions relating to individual investors who invest in Indian stock market. The present study assesses the influence of aforesaid behavioural biases on investment decisions made by individual investors. The study is based on a questionnaire investigation by including the individual investors of Indian stock market residing in Bihar (India) using a convenient sampling technique. 500 hundred questionnaires have been distributed among the individual investors and 428 responses has been taken into consideration for the present study. The collected data were analysed through multiple regression using SPSS. The present study found that the scale used to measure behavioural biases and investment decisions of individual investors were valid and overconfidence biases have a significant influence on investment decisions of individual investors. In contrary, herding effect and loss aversion does not significantly influence the investment decision of individual investor. The present study found that the individual investors are behaviourally biased while making investment decisions. The present study backs to the academia of behavioural aspects and individual investors who invest in Indian stock market. The present study supports in understanding the concept of behavioural biases of individual investors investing in Indian stock market.