The purpose of this study is to determine the defect rate of kernel products at PT. Inti Indosawit Subur is still under control or not through the control chart-R and to find out what factors cause the failure of kernel products at PT. Inti Indosawit Subur through a causal diagram. The method used is descriptive quantitative with the data analysis method used, namely the control map-R to see abnormalities or deviations in the kernel quality data and cause and effect diagrams to analyze what are the causes of product defects. The data collection methods used in the writing of this study were field research (interviews and documentation) and literature study. Based on the results of the analysis of the cause and effect diagram for the standard broken kernel, the following factors cause broken kernel defects in terms of the work environment, and humans, namely: Work Method Factors,(1) Error setting ripple mill and screw press, errors that occur. Occurs in the ripple mill and screw press, namely:(a) Incorrect density setting in the ripple mill.(b) Incorrect pressure setting in screw press.(2) The boiling method is too long. Work Environment Factors (1) The condition of the workplace is not proper.(2) Work area in a heat sterilizer station. The hot work area, even the temperature reaching 143 C, is actually quite disturbing for employees to work as a result, the workforce spent by employees working in this section is large enough so that they will experience fatigue faster. The fatigue seized by these employees will damage the concentration in working even though the sterilizer station must be operated optimally, because the good and bad quality of kernels, especially broken kernels, depend on the boiling process.(3) The sound of the production machines is too loud. The sound of a machine that is very disturbing in controlling kernel quality for broken kernels is the ripple mill. Human Factor. Omission of the sterilizer section. Just like the quality standard of negligence dirt level also occurs in the sterilizer section, this is due to the employee's unhealthy condition or exhaustion so that he is unable to run or operate the sterilizer with SOP (Standard Operating Procedure) rules.