Kendall Jenner thinks Caitlyn Jenner's memoir is ''insane''.

The 67-year-old reality star - who was formerly known as Bruce Jenner before undergoing gender reassignment - recently released her memoir 'Secrets of My Life' in which she details her relationship with ex-wife Kris Jenner, with whom she had two daughters, Kendall, 21, and Kylie, 19.

Now, in a preview clip for an upcoming episode of 'Keeping Up with the Kardashians', Kendall can be heard telling her 61-year-old mother the contents of the book is ''insane''.

In one clip, Kendall asks her half-sister Kim Kardashian West: ''You read the whole thing? What did she say?''

The camera then cuts to the model sat in the kitchen with Kris, where she says: ''It's insane mom! That's insane!''

Kendall's shock at the contents of the memoir comes after Kim, 36, recently blasted her former step-father for including details of her relationship with Kris in her book, as she believes Caitlyn is wrong to ''bash other people'' in her writing.

Kim said previously: ''That was my stepdad for so many years. She taught me about character and so much growing up, and I just feel like I don't respect the character that she's showing now ... like there's no need for a book. Tell your story, but just don't bash other people I just think it's not tasteful.''

The brunette beauty also said her ''heart breaks'' for her mother Kris, who has to hear all these ''untruthful'' things.

She added: ''My heart breaks for my mom because I feel like she's been through so much. Caitlyn's promoting this book and she's saying all these things. And I just don't think it's necessary. I just feel like it's unfair, things aren't truthful.

''I feel like it's taken her a really long time to be honest with herself, so I don't expect her to be honest about my mom now ... But it's just so hurtful. I wish her all the success in the world, but not at our expense.''