This study investigated the types of pronunciation error and factors
causing pronunciation error as seen in the video. Pronunciation error in
this study referred to error in producing English diphthong. The
research subjects of this study were the third semester students of
STKIP PGRI Sidoarjo. This study was a descriptive qualitative study
because this study aimed to describe the findings. Documentation
analysis was the technique of collecting data of this study. The
researcher was the main instrument of this study. The researcher used
theories of English diphthong by Gerald Kelly and Yulianto Sabat and
theories of factors causing pronunciation error by Ladefoged. The steps
of data analysis of this study were the identification, classification, and
description. The results of this study showed that the researcher found 2
types of pronunciation error that were substitution and omission. The
researcher also found 3 factors that caused pronunciation error. Those
factors are (1) the influence of spelling English pronunciation, (2) The
sound system differences between L1 and L2, (3) the inconsistency of
English vowels